Internet DRAFT - draft-pinkas-smime-cades

draft-pinkas-smime-cades



S/MIME Working Group                      J.Ross(Security and Standards)
INTERNET-DRAFT                            N.Pope(Security and Standards)
Expires February 2006                                     D.Pinkas(Bull)
Obsoletes: RFC 3126                                          August 2005
Target Category: Informational





              CMS Advanced Electronic Signatures (CAdES)
                   <draft-pinkas-smime-cades-01.txt>




Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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   This document may not be modified, and derivative works of it may
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Abstract

   This document defines the format of an electronic signature that can
   remain valid over long periods.  This includes evidence as to its
   validity even if the signer or verifying party later attempts to deny
   (i.e., repudiates the validity of the signature). The format can be
   considered as an extension to RFC 3369 and RFC 2634, where, when
   appropriate additional signed and unsigned attributes have been
   defined.  The contents of this Informational RFC amounts to a 
   transposition of the ETSI TS 101 733 V.1.6.3 (CMS Advanced 
   Electronic Signatures - CAdES) and is technically equivalent to it.



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   Table of Contents


1.  Introduction                                                      6

2.  Scope                                                             6

3.  Definitions and abbreviations                                     8
3.1  Definitions                                                      8
3.2  Abbreviations                                                   11

4.  Overview                                                         12
4.1  Major parties                                                   12
4.2  Signatures policies                                             14
4.3  Electronic signature formats                                    14
4.3.1  CAdES Basic Electronic Signature (CAdES-BES)                  14
4.3.2  CAdES Explicit Policy Electronic Signatures (CAdES-EPES)      17
4.4  Electronic signature formats with validation data               18
4.4.1  Electronic Signature with Time (CAdES-T)                      19
4.4.2  ES with Complete validation data references (CAdES-C)         20
4.4.3  Extended electronic signature formats                         22
4.4.4  Archival Electronic Signature (CAdES-A)                       26
4.5  Arbitration                                                     27
4.6  Validation process                                              28

5.  Electronic signature attributes                                  29
5.1  General syntax                                                  29
5.2  Data content type                                               29
5.3  Signed-data content type                                        29
5.4  SignedData type                                                 30
5.5  EncapsulatedContentInfo type                                    30
5.6  SignerInfo type                                                 30
5.6.1  Message digest calculation process                            31
5.6.2  Message signature generation process                          31
5.6.3  Message signature verification process                        31
5.7  Basic ES mandatory present attributes                           31
5.7.1  Content type                                                  31
5.7.2  Message digest                                                31
5.7.3  Signing certificate reference attribute                       31
5.8  Additional mandatory attributes for Explicit Policy-based         
     Electronic Signatures                                           33
5.8.1  Signature policy identifier                                   33
5.9  CMS imported optional attributes                                35
5.9.1  Signing time                                                  35
5.9.2  Countersignature                                              35
5.10  ESS imported optional attributes                               36
5.10.1  Content reference attribute                                  36
5.10.2  Content identifier attribute                                 36
5.10.3  Content hints attribute                                      36




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5.11  Additional optional attributes defined in the present document 37
5.11.1  Commitment type indication attribute                         37
5.11.2  Signer location attribute                                    39
5.11.3  Signer attributes attribute                                  40
5.11.4  Content time-stamp                                           40
5.12  Support for multiple signatures                                41
5.12.1  Independent signatures                                       41
5.12.2  Embedded signatures                                          41

6.  Additional Electronic Signature validation attributes            41
6.1  Electronic Signature Time-stamped (CAdES-T)                     43
6.1.1  Signature time- stamp attribute definition                    43
6.2  Complete validation reference data (CAdES-C)                    44
6.2.1  Complete certificate references attribute definition          44
6.2.2  Complete Revocation References attribute definition           45
6.2.3  Attribute certificate references attribute definition         47
6.2.4  Attribute revocation references attribute definition          47
6.3  Extended validation data (CAdES-X)                              48
6.3.1  Time-stamped validation data (CAdES-X Type 1 or Type 2)       48
6.3.2  Long validation data (CAdES-X Long, CAdES-X Long Type 1 or 2) 48
6.3.3  Certificate values attribute definition                       49
6.3.4  Revocation values attribute definition                        50
6.3.5  CAdES-C time-stamp attribute definition                       51
6.3.6  Time-stamped certificates and crls references attribute         
       definition                                                    51
6.4  Archive validation data                                         52
6.4.1  Archive time-stamp attribute definition                       52

7.  Other standard data structures                                   54
7.1  Public-key certificate format                                   54
7.2  Certificate revocation list format                              54
7.3  OCSP response format                                            54
7.4  Time-stamp token format                                         54
7.5  Name and attribute formats                                      54
7.6  Attribute certificate                                           55

8.  Conformance requirements                                         55
8.1  CAdES-Basic Electronic Signature (CAdES-BES)                    56
8.2  CAdES-Explicit Policy-based Electronic Signature                56
8.3  Verification using time-stamping                                56
8.4  Verification using secure records                               57

9.  Security considerations                                          58
9.1  Protection of private key                                       58
9.2  Choice of algorithms                                            58

10.  IANA Considerations                                             58

11.  References                                                      58
11.1  Normative references                                           58
11.2  Informative references                                         59

12.  Authors' addresses                                              62


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Annex A (normative): ASN.1 definitions                               63
A.1  Signature format definitions using X.208 ASN.1 syntax           63
A.2  Signature format definitions using X.680 ASN.1 syntax           72

Annex B (informative): Extended forms of Electronic Signatures       81
B.1  Extended forms of validation data                               81
B.1.1  CAdES-X Long                                                  82
B.1.2  CAdES-X Type 1                                                83
B.1.3  CAdES-X Type 2                                                84
B.1.4  CAdES-X Long Type 1 and CAdES-X Long Type 2                   85
B.2  Timestamp extensions                                            87
B.3  Archive validation data (CAdES-A)                               88
B.4  Example validation sequence                                     90
B.5  Additional optional features                                    95

Annex C (informative):General description                            96
C.1  The signature policy                                            96
C.2  Signed information                                              97
C.3  Components of an electronic signature                           97
C.3.1  Reference to the signature policy                             97
C.3.2  Commitment type indication                                    98
C.3.3  Certificate identifier from the signer                        98
C.3.4  Role attributes                                               99
C.3.4.1  Claimed role                                                99
C.3.4.2  Certified role                                             100
C.3.5  Signer location                                              100
C.3.6  Signing time                                                 100
C.3.7  Content format                                               101
C.3.8  Content cross referencing                                    101
C.4  Components of validation data                                  101
C.4.1  Revocation status information                                101
C.4.1.1  CRL information                                            102
C.4.1.2  OCSP information                                           102
C.4.2  Certification path                                           103
C.4.3  Time-stamping for long life of signatures                    103
C.4.4  Time-stamping for long life of signature before CA key          
       compromises                                                  104
C.4.4.1  Time-stamping the ES with complete validation data         105
C.4.4.2  Time-stamping certificates and revocation information         
         references                                                 106
C.4.5  Time-stamping for archive of signature                       107
C.4.6  Reference to additional data                                 108
C.4.7  Time-stamping for mutual recognition                         108
C.4.8  TSA key compromise                                           109
C.5  Multiple signatures                                            109

Annex D (informative):Data protocols to interoperate with TSPs      110
D.1  Operational protocols                                          110
D.1.1  Certificate retrieval                                        110
D.1.2  CRL retrieval                                                110
D.1.3  OnLine certificate status                                    110
D.1.4  Time-stamping                                                110
D.2  Management protocols                                           110
D.2.1  Request for certificate revocation                           110

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Annex E (informative): Guidance on naming                           111
E.1  Allocation of names                                            111
E.2  Providing access to registration information                   111
E.3  Naming schemes                                                 112
E.3.1  Naming schemes for individual citizens                       112
E.3.2  Naming schemes for employees of an organization              113

Annex F (informative): Example structured contents and MIME         114
F.1  General description                                            114
F.2  Header information                                             114
F.3  Content encoding                                               115
F.4  Multi-part content                                             115
F.5  S/MIME                                                         116

Annex G (informative): Relationship to the European Directive          
                       And EESSI                                    119
G.1  Introduction                                                   119
G.2  Electronic signatures and the directive                        119
G.3  ETSI electronic signature formats and the directive            120
G.4  EESSI standards and classes of electronic signature            120
G.4.1  Structure of EESSI standardization                           120
G.4.2  Classes of electronic signatures                             121
G.4.3  EESSI classes and the ETSI electronic signature format       121

Annex H (informative): APIs for the generation and verification        
                       of electronic signatures tokens              122
H.1  Data framing                                                   122
H.2  IDUP-GSS-APIs defined by the IETF                              123
H.3  CORBA security interfaces defined by the OMG                   124

Annex I (informative):Cryptographic algorithms                      126
I.1  Digest algorithms                                              126
I.1.1  SHA-1                                                        126
I.1.2  General                                                      126
I.2  Digital signature algorithms                                   127
I.2.1  DSA                                                          127
I.2.2  RSA                                                          127
I.2.3  General                                                      128

Annex J (informative): Changes from the previous version            130

Full Copyright Statement                                            131

Disclaimer                                                          131

Intellectual Property                                               131









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1. Introduction

This document is intended to cover electronic signatures for various
types of transactions, including business transactions (e.g. purchase
requisition, contract, and invoice applications) where long term
validity of such signatures is important.  This includes evidence as
to its validity even if the signer or verifying party later attempts
to deny (i.e., repudiates, see ISO/IEC 10181-5) the validity of the
signature).

Thus the present document can be used for any transaction between an 
individual and a company, between two companies, between an individual 
and a governmental body, etc.  The present document is independent of 
any environment. It can be applied to any environment e.g. smart cards, 
GSM SIM cards, special programs for electronic signatures, etc.

The European Directive on a community framework for Electronic 
Signatures defines an electronic signature as: "Data in electronic form 
which is attached to or logically associated with other electronic data 
and which serves as a method of authentication". 

An electronic signature as used in the present document is a form 
of advanced electronic signature as defined in the Directive.

The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase,
as shown) are to be interpreted as described in RFC 2119 [STDWORDS]

2. Scope

The scope the present document covers Electronic Signature Formats 
only.  The aspects of Electronic Signature Policies are defined in RFC 
3125 and in TR 102 272 (see informative references).

The present document defines a number of Electronic Signature Formats, 
including electronic signature that can remain valid over long periods. 
This includes evidence as to its validity even if the signer or 
verifying party later attempts to deny (repudiates) the validity of the 
electronic signature.

The present document specifies use of trusted service providers (e.g. 
Time-Stamping Authorities), and the data that needs to be archived 
(e.g. cross certificates and revocation lists) to meet the requirements 
of long term electronic signatures.

An electronic signature defined by the present document can be used for 
arbitration in case of a dispute between the signer and verifier, which 
may occur at some later time, even years later. 






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The present document includes the concept of signature policies that 
can be used to establish technical consistency when validating 
electronic signatures but does not mandate their use.

The present document is based on the use of public key cryptography to 
produce digital signatures, supported by public key certificates.
The present document also specifies the use of time-stamping and time-
marking services to prove the validity of a signature long after the 
normal lifetime of critical elements of an electronic signature.  It 
also, as an option, defines ways to provide very long-term protection 
against key compromise or weakened algorithms.

The present document builds on existing standards that are widely 
adopted. This includes:

    - RFC 3852 [4] "Cryptographic Message Syntax (CMS)";

    - ISO/IEC 9594-8/ITU-T Recommendation X.509 [1]: "Information 
      technology - Open Systems Interconnection - The Directory: 
      Authentication framework";

    - RFC 3280 [2] "Internet X.509 Public Key Infrastructure (PKIX) 
      Certificate and CRL Profile";

    - RFC 3161 [7] "Internet X.509 Public Key Infrastructure Time-Stamp 
      Protocol (TSP)".

 NOTE: See section 11 for a full set of references.

The present document describes formats for advanced electronic 
signatures using ASN.1 (Abstract Syntax Notation 1).  These formats are 
based on CMS (Cryptographic Message Syntax) defined in RFC 3852 [4]. 
These electronic signatures are thus called CAdES, for "CMS Advanced 
Electronic Signatures".

Another document, TS 101 903 (see informative references), describes 
formats for XML advanced electronic signatures (XAdES) built on 
XMLDSIG.

In addition, the present document identifies other documents that 
define formats for Public Key Certificates, Attribute Certificates, 
Certificate Revocation Lists and supporting protocols, including, 
protocols for use of trusted third parties to support the operation of 
electronic signature creation and validation.










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Informative annexes include:

   - illustrations of extended forms of extended Electronic Signatures 
     formats that protect against various vulnerabilities and examples 
     of validation processes;

   - descriptions and explanations of some of the concepts used in the 
     present document. giving a rational for normative parts of the 
     present document;

   - information on protocols to interoperate with Trusted Service 
     Providers;

   - information on security considerations;

   - an example structured content and MIME;

   - the relationship between the present document and the directive 
     on electronic signature and associated standardization 
     initiatives;

   - APIs to support the generation and the verification of electronic 
     signatures;

   - cryptographic algorithms that may be used;

   - guidance on naming.

   - changes from the previous version.

3 Definitions and abbreviations

3.1 Definitions

For the purposes of the present document, the following terms and 
definitions apply:

Arbitrator: arbitrator entity may be used to arbitrate a dispute 
between a signer and verifier when there is a disagreement on the 
validity of a digital signature.

Attribute Authority (AA): authority which assigns privileges by issuing 
attribute certificates.

Authority certificate: certificate issued to an authority (e.g. either 
to a certification authority or to an attribute authority).

Attribute Authority Revocation List (AARL): revocation list containing 
a list of references to certificates issued to AAs, that are no longer 
considered valid by the issuing authority.



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Attribute Certificate Revocation List (ACRL): revocation list 
containing a list of references to attribute certificates that are no 
longer considered valid by the issuing authority.

Certification Authority Revocation List (CARL): revocation list 
containing a list of public-key certificates issued to certification 
authorities, that are no longer considered valid by the certificate 
issuer.

Certification Authority (CA): authority trusted by one or more users to 
create and assign public key certificates, optionally the certification 
authority may create the users' keys.

 NOTE: See ITU-T Recommendation X.509 [1].

Certificate Revocation List (CRL): signed list indicating a set of 
public key certificates that are no longer considered valid by the 
certificate issuer.

Digital signature: data appended to, or a cryptographic transformation 
of, a data unit that allows a recipient of the data unit to prove the 
source and integrity of the data unit and protect against forgery, e.g. 
by the recipient.

 NOTE: See ISO 7498-2 (see informative references).

Electronic signature: data in electronic form which are attached to or 
logically associated with other electronic data and which serve as a 
method of authentication.

 NOTE: See Directive 1999/93/EC of the European Parliament and of the 
       Council of 13 December 1999 on a Community framework for 
       electronic signatures.

Enhanced electronic signatures: electronic signatures enhanced by 
complementing the baseline requirements with additional data, such as 
time tamp tokens and certificate revocation data, to address commonly 
recognized threats.

Explicit Policy-based Electronic Signature (EPES): an electronic 
signature where the signature policy is explicitly specified that shall 
be used to validate it.

grace period: time period which permits the certificate revocation 
information to propagate through the revocation process to relying 
parties.

Initial verification: a process performed by a verifier done after an 
electronic signature is generated in order to capture additional 
information that could make it valid for long term verification.




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Public Key Certificate (PKC): public keys of a user, together with some 
other information, rendered unforgeable by encipherment with the 
private key of the certification authority which issued it. 

 NOTE: See ITU-T Recommendation X.509 [1].

Rivest-Shamir-Adleman (RSA): asymmetric cryptography algorithm based on 
the difficulty to factorize very large numbers, using a key pair: a 
private key and a public key.

Signature policy: set of rules for the creation and validation of an 
electronic signature, that defines the technical and procedural 
requirements for electronic signature creation and validation, in order 
to meet a particular business need, and under which the signature can 
be determined to be valid.

Signature policy issuer: entity that defines and issues a signature 
policy.

Signature validation policy: part of the signature policy which 
specifies the technical requirements on the signer in creating a 
signature and verifier when validating a signature.

Signer: entity that creates an electronic signature.

Subsequent Verification: a process performed by a verifier to assess 
the signature validity.

 NOTE: It may be done even years after the electronic signature was 
       produced by the signer and completed by the Initial 
       Verification and it might not need to capture more data than 
       those captured at the time of initial verification.

Time-Stamp token: data object that binds a representation of a datum to 
a particular time, thus establishing evidence that the datum existed 
before that time.

Time-Mark: information in an audit trail from a Trusted Service 
Provider that binds a representation of a datum to a particular time, 
thus establishing evidence that the datum existed before that time.

Time-Marking Authority: trusted third party that creates records in an 
audit trail in order to indicate that a datum existed before a 
particular point in time.

Time-Stamping Authority (TSA): trusted third party that creates time-
stamp tokens in order to indicate that a datum existed at a particular 
point in time.




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Time-Stamping Unit (TSU): set of hardware and software which is managed 
as a unit and has a single time-stamp token signing key active at a 
time.

Trusted Service Provider (TSP): entity that helps to build trust 
relationships by making available or providing some information upon 
request.

Validation data: additional data that may be used by a verifier of 
electronic signatures to determine the signature is valid.

Valid electronic signature: electronic signature which passes 
validation.

Verifier: entity that verifies evidence.

 NOTE 1: See ISO/IEC 13888-1 (see informative references).

 NOTE 2: Within the context of the present document this is an entity 
         that validates an electronic signature.

3.2 Abbreviations

For the purposes of the present document, the following abbreviations 
apply:

AA          Attribute Authority
AARL        Attribute Authority Revocation List
ACRL        Attribute Certificate Revocation List
API         Application Program Interface
ASCII       American Standard Code for Information Interchange 
ASN.1       Abstract Syntax Notation 1
CA          Certification Authority
CAD         Card Accepting Device
CAdES       CMS Advanced Electronic Signature
CAdES-A     CAdES with Archive validation data
CAdES-BES   CAdES Basic Electronic Signature
CAdES-C     CAdES with Complete validation data 
CAdES-EPES  CAdES Explicit Policy Electronic Signature
CAdES-T     CAdES with Time-stamp 
CAdES-X     CAdES with eXtended validation data
CARL        Certification Authority Revocation List
CMS         Cryptographic Message Syntax
CRL         Certificate Revocation List
CWA         CEN Workshop Agreement
DER         Distinguished Encoding Rules (for ASN.1)
DSA         Digital Signature Algorithm 
EDIFACT     Electronic Data Interchange For Administration, Commerce 
            and Transport





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EESSI       European Electronic Signature Standardization Initiative
EPES        Explicit Policy-based Electronic Signature
ES          Electronic Signature
ESS         Enhanced Security Services (enhances CMS)
IDL         Interface Definition Language
MIME        Multipurpose Internet Mail Extensions
OCSP        Online Certificate Status Provider 
OID         Object IDentifier
PKC         Public Key Certificate
PKIX        internet X.509 Public Key Infrastructure
RSA         Rivest-Shamir-Adleman
SHA-1       Secure Hash Algorithm 1
TSA         Time-Stamping Authority
TSP         Trusted Service Provider
TST         Time-Stamp Token
TSU         Time-Stamping Unit
URI         Uniform Resource Identifier
URL         Uniform Resource Locator
XML         eXtended Mark up Language
XMLDSIG     XML-Signature Syntax and Processing


4 Overview

The present document defines a number of Electronic Signature (ES) 
formats that build on CMS (RFC 3852 [4] by adding signed and unsigned 
attributes.

This clause provides an introduction to the major parties involved 
(clause 4.1), the concept of Signature Policies (clause 4.2), provides 
an overview of the various ES formats (clause 4.3), introduces the 
concept of validation data and provides an overview of formats that 
incorporate validation data (clause 4.4), presents relevant 
considerations on arbitration (clause 4.5) and for the validation 
process (clause 4.6).

The formal specifications of the attributes are specified in clauses 5 
and 6, annexes C and D provide rationale for the definitions of the 
different ES forms.

4.1 Major parties

The major parties involved in a business transaction supported by 
electronic signatures as defined in the present document are:

   - the Signer;
   - the Verifier;
   - Trusted Service Providers (TSP);
   - the Arbitrator.




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The signer is the entity that creates the electronic signature.  When 
the signer digitally signs over data using the prescribed format, this 
represents a commitment on behalf of the signing entity to the data 
being signed.

The verifier is the entity that validates the electronic signature, it 
may be a single entity or multiple entities.

The Trusted Service Providers (TSPs) are one or more entities that help 
to build trust relationships between the signer and verifier.  They 
support the signer and verifier by means of supporting services 
including: user certificates, cross-certificates, time-stamp tokens, 
CRLs, ARLs, OCSP responses.  The following TSPs are used to support the 
functions defined in the present document:

   - Certification Authorities;
   - Registration Authorities;
   - Repository Authorities (e.g. a Directory);
   - Time-Stamping Authorities;
   - Time-Marking Authorities;
   - Signature Policy Issuers.

Certification Authorities provide users with public key certificates 
and with a revocation service.

Registration Authorities allow the identification and registration of 
entities before a CA generates certificates.

Repository Authorities publish CRLs issued by CAs, signature policies 
issued by Signature Policy Issuers and optionally public key 
certificates.

Time-Stamping Authorities attest that some data was formed before a 
given trusted time.

Time-Marking Authorities record that some data was formed before a 
given trusted time.

Signature Policy Issuers define the signature policies to be used by 
signers and verifiers.

In some cases the following additional TSPs are needed:

   - Attribute Authorities.

Attributes Authorities provide users with attributes linked to public 
key certificates.

An Arbitrator is an entity that arbitrates in disputes between a signer 
and a verifier.



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4.2 Signatures policies

The present document includes the concept of signature policies that 
can be used to establish technical consistency when validating 
electronic signatures. 

When a comprehensive signature policy used by the verifier is either 
explicitly indicated by the signer or implied by the data being signed, 
then a consistent result can be obtained when validating an electronic 
signature. 

When the signature policy being used by the verifier is neither 
indicated by the signer nor can be derived from other data, or the 
signature policy is incomplete then verifiers, including arbitrators, 
may obtain different results when validating an electronic signature. 
Therefore, comprehensive signature policies that ensure consistency of 
signature validation are recommended from both the signers and 
verifiers point of view. 

Further information on signature policies is provided in:

   - TR 102 038 (see informative references);
   - Clauses 5.8.1, C.1 and C.3.1 of the present document;
   - RFC 3125 (see informative references);
   - TR 102 272 (see informative references).

4.3 Electronic signature formats

The current clause provides an overview for two forms of CMS advanced 
electronic signature specified in the present document, namely, the 
CAdES Basic Electronic Signature (CAdES-BES) and the CAdES Explicit 
Policy-based Electronic Signature (CAdES-EPES).  Conformance to the 
present document mandates the signer creates one of these formats.

4.3.1 CAdES Basic Electronic Signature (CAdES-BES)

A CAdES Basic Electronic Signature (CAdES-BES) in accordance with the 
present contains:

   - The signed user data (e.g. the signer's document) as defined in 
     CMS (RFC 3852 [4]);

   - A collection of mandatory signed attributes as defined in CMS 
    (RFC 3852 [4]).and in ESS (RFC 2634 [5]);

   - Additional mandatory signed attributes defined in the present 
     document;






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   - The digital signature value computed on the user data and, when 
     present, on the signed attributes, as defined in CMS (RFC 3852 
     [4]).

A CAdES Basic Electronic Signature (CAdES-BES) in accordance with the 
present may contain:

   - A collection of additional signed attributes;
   - A collection of optional unsigned attributes.

The mandatory signed attributes are:

   - Content-type.  It is defined in RFC 3852 [4] and specifies that 
     the content type of the ContentInfo is "signed-data".  Details 
     are provided in clause 5.7.1;

   - Message-digest.  It is defined in RFC 3852 [4] and specifies the 
     message digest of the eContent OCTET STRING within 
     encapContentInfo being signed.  Details are provided in clause 
     5.7.2;

   - ESS signing-certificate OR other-signing-certificate.  The ESS 
     signing-certificate attribute is defined in Enhanced Security 
     Services (ESS), RFC 2634 [5] and only allows for the use of SHA-1 
     as digest algorithm.  The other-signing-certificate attribute one 
     is defined in the present document and allows for the use of any 
     digest algorithm.  A CAdES-BES claiming compliance with the 
     present document must include one of them.  Clause 5.7.3 provides 
     the details of these attributes.  Clause 5.7.3.2 shows the formal 
     specification of other-signing-certificate.  Rationale for its 
     inclusion is provided in clause C.3.3.

Optional signed attributes may be added to the CAdES-BES, including 
optional signed attributes defined in CMS (RFC 3852 [4]), (RFC 2634 
[5]) and the present document.  Listed below are optional attributes 
that are defined in clause 5 and have a rational provided in annex C:

   - Signing-time: as defined in CMS (RFC 3852 [4]) indicates the time 
     of the signature as claimed by the signer.  Details and short 
     rationale are provided in clause 5.9.1.  Clause C.3.6 in provides 
      the rationale.

   - Content-hints as defined in ESS (RFC 2634 [5]) provides 
     information that describes the format of the signed content. 
     Clause 5.10.1 provides the specification details.  Clause C.3.7 
     in provides the rationale.







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   - Content-reference.  as defined in ESS (RFC 2634 [5]) can be 
     incorporated as a way to link request and reply messages in an 
     exchange between two parties.  Clause 5.10.1 provides the 
     specification details.  Clause C.3.8 in provides the rationale.

   - Content-identifier.  as defined in ESS (RFC 2634 [5]) contains an 
     identifier that may be used later on in the previous content-
     reference attribute.  Clause 5.10.2 provides the specification 
     details.  Clause C.3.8 in provides the rationale.

   - Commitment-type-indication.  This attribute is defined by the 
     present document as a way to indicate the commitment endorsed by 
     the signer when producing the signature.  Clause 5.11.1 provides 
     the specification details.  Clause C.3.2 in provides the 
     rationale.

   - Signer-location.  This attribute is defined by the present 
     document.  It allows the signer to indicate the place where he 
     has purportedly produced the signature.  Clause 5.11.2 provides 
     the specification details.  Clause C.3.5 provides the rationale.

   - Signer-attributes.  This attribute is defined by the present 
     document.  It allows a claimed or certified role to be 
     incorporated into the signed information.  Clause 5.11.3 provides 
     the specification details.  Clause C.3.4 provides the rationale.

   - Content-time-stamp.  This attribute is defined by the present 
     document.  It allows a time-stamp token of the data to be signed 
     to be incorporated into the signed information.  It provides 
     proof of the existence of the data before the signature was 
     created.  Clause 5.11.4 provides the specification details.  
     Clause C.3.6 provides the rationale.

A CAdES-BES form can also incorporate instances of unsigned attributes 
as defined in CMS (RFC 3852 [4]) and (RFC 2634 [5]).

   - CounterSignature.  as defined in CMS (RFC 3852 [4]).  It can be 
     incorporated wherever allowing embedded signatures is a 
     requirement.  Clause 5.9.2 provides the specification details.  
     Clause C.5 in annex C provides the rationale.

The structure of the CAdES-BES is illustrated in figure 1.










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             +------Elect.Signature (CAdES-BES)------+
             |+----------------------------------- + |
             ||+---------+ +----------+            | |
             |||Signer's | |  Signed  |  Digital   | |
             |||Document | |Attributes| Signature  | |
             |||         | |          |            | |
             ||+---------+ +----------+            | |
             |+------------------------------------+ |
             +---------------------------------------+

               Figure 1: Illustration of a CAdES-BES


The signer's conformance requirements of a CAdES-BES are defined in 
clause 8.1.
 NOTE: The CAdES-BES is the minimum format for an electronic signature 
       to be generated by the signer.  On its own, it does not 
       provide enough information for it to be verified in the longer 
       term.  For example, revocation information issued by the 
       relevant certificate status information issuer needs to be 
       available for long term validation (see clause 4.4.2).

The CAdES-BES satisfies the legal requirements for electronic 
signatures as defined in the European Directive on electronic 
signatures, (see annex C for further discussion on relationship of the 
present document to the Directive).  It provides basic authentication 
and integrity protection.

The semantics of the signed data of a CAdES-BES or its context may 
implicitly indicate a signature policy to the verifier.  Specification 
of the contents of signature policies is outside the scope of the 
present document.

Further information on signature policies is provided in TR 102 038 
(see informative references), RFC 3125 (see informative references) and 
clauses 5.8.1, C.1 and C.3.1 of the present document.

4.3.2 CAdES Explicit Policy Electronic Signatures (CAdES-EPES)

A CAdES Explicit Policy-based Electronic Signature (CAdES-EPES) in 
accordance with the present document, extends the definition of an 
electronic signature to conform to the identified signature policy.  
A CAdES Explicit Policy-based Electronic Signature (CAdES-EPES) 
incorporates a signed attribute (signature-policy-identifier) 
indicating that a signature policy that is mandatory to use to validate 
the signature and specifies explicitly the signature policy that shall 
be used.  This signed attribute is protected by the signature.  The 
signature may also have other signed attributes required to conform to 
the mandated signature policy.



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Clause 5.7.3 provides the details on the specification of signature-
policy-identifier attribute.  Clause C.1 provides a short rationale. 
Specification of the contents of signature policies is outside the 
scope of the present document.

Further information on signature policies is provided in TR 102 038 
(see informative references) and clauses 5.8.1, C.1 and C.3.1 of the 
present document.

The structure of the CAdES-EPES is illustrated in figure 2.

       +------------- Elect.Signature (CAdES-EPES) ---------------+
       ||+----------------------------------------------------- + |
       ||                 +---------------------------+         | |
       || +---------+     |   +----------+            |         | |
       || |         |     |   |          |            |         | |
       || |Signer's |     |   |Signature | Signed     | Digital | |
       || |Document |     |   |Policy ID | Attributes |Signature| |
       || |         |     |   |          |            |         | |
       || +---------+     |   +----------+            |         | |
       ||                 +---------------------------+         | |
       |+-------------------------------------------------------+ |
       |                                                          |
       +----------------------------------------------------------+

                Figure 2: Illustration of a CAdES-EPES


The signer's conformance requirements of CAdES-EPES are defined in 
clause 8.2.

4.4 Electronic signature formats with validation data

Validation of an electronic signature in accordance with the present 
document requires additional data needed to validate the electronic 
signature.  This additional data is called validation data; and 
includes:

   - Public Key Certificates (PKCs);

   - revocation status information for each PKC;

   - trusted time-stamps applied to the digital signature or a time-
     mark shall be available in an audit log;

   - when appropriate, the details of a signature policy to be used to 
     verify the electronic signature.






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The validation data may be collected by the signer and/or the verifier. 
When the signature policy id is present, it shall meet the requirements 
of the signature policy.  Validation data includes CA certificates as 
well as revocation status information in the form of Certificate 
Revocation Lists (CRLs) or certificate status information (OCSP) 
provided by an on-line service.  Validation data also includes evidence 
that the signature was created before a particular point in time this 
may be either a time-stamp token or time-mark.

The present document defines unsigned attributes able to contain 
validation data that can be added to CAdES-BES and CAdES-EPES leading 
to electronic signature formats that include validation data.  Clauses 
below summarize these formats and their most relevant characteristics.

4.4.1 Electronic Signature with Time (CAdES-T)

Electronic Signature with Time (CAdES-T) in accordance with the present 
document is when there exits trusted time associated with the ES.

The trusted time may be provided by:

   - the signature-time-stamp as an unsigned attribute added to the 
     ES;

   - A time mark of the ES provided by a trusted service provider.

The signature-time-stamp attribute contains a time-stamp token of the 
electronic signature value.  Clause 6.1.1 provides the specification 
details.  Clause C.4.3 in provides the rationale.

A time-mark provided by a Trusted Service would have similar effect to 
the signature-time-stamp attribute but in this case no attribute is 
added to the ES as it is the responsibility of the TSP to provide 
evidence of a time mark when required to do so.  The management of time 
marks is outside the scope of the present document.

Trusted time provides the initial steps towards providing long term 
validity.  Electronic signatures with the time stamp attribute forming 
the CAdES-T is illustrated in figure 3.














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  +-------------------------------------------------CAdES-T ---------+
  |+------ CAdES-BES or CAdES-EPES -------+                          |
  ||+-----------------------------------+ | +----------------------+ |
  |||+---------+ +----------+           | | |                      | |
  ||||Signer's | |  Signed  |  Digital  | | | Signature-time-stamp | |
  ||||Document | |Attributes| Signature | | | attribute required   | |
  ||||         | |          |           | | | when using time      | |
  |||+---------+ +----------+           | | | stamps.              | |
  ||+-----------------------------------+ | |                      | |
  |+--------------------------------------+ | or the BES/EPES      | |
  |                                         | shall be tme marked  | |
  |                                         |                      | |
  |                                         | Management and       | |
  |                                         | provision of time    | |
  |                                         | mark is the          | |
  |                                         | responsibility of    | |
  |                                         | the TSP.             | |
  |                                         +----------------------+ |
  +------------------------------------------------------------------+

               Figure 3: Illustration of CAdES-T formats


 NOTE  A time stamp token is added to the CAdES-BES or CAdES-EPES as 
       an unsigned attribute.

4.4.2 ES with Complete validation data references (CAdES-C)

Electronic Signature with Complete validation data references (CAdES-C) 
in accordance with the present document adds to the CAdES-T the 
complete-certificate-references and complete-revocation-references 
attributes as defined by the present document.  The complete-
certificate-references attribute contain references to all the 
certificates present in the certification path used for verifying the 
signature.  The complete-revocation-references attribute contains 
references to the CRLs and/or OCSP responses used for verifying the 
signature.  Clause 6.2 provides the specification details.  Storing the 
references allows the values of the certification path and the CRLs or 
OCSPs responses to be stored elsewhere, reducing the size of a stored 
electronic signature format.

Clauses C.4.1 to C.4.2 provide rationale on the usage of validation 
data and when it is suitable to generate the CAdES-C form.
Electronic signatures with the additional validation data forming the 
CAdES-C are illustrated in figure 4. 








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  +------------------------- CAdES-C --------------------------------+
  |+----------------------------- CAdES-T ---------+                 |
  ||                                  +----------+ | +-------------+ |
  ||                                  |Timestamp | | |             | |
  ||                                  |attribute | | |             | |
  ||+- CAdES-BES or CAdES-EPES ------+|over      | | |             | |
  |||                                ||digital   | | | Complete    | |
  |||+---------++----------+         ||signature | | | certificate | |
  ||||Signer's ||  Signed  | Digital ||is        | | |     and     | |
  ||||Document ||Attributes|Signature||mandatory | | | revocation  | |
  ||||         ||          |         ||if is     | | | references  | |
  |||+---------++----------+         ||NOT       | | |             | |
  ||+--------------------------------+|timemarked| | |             | |
  ||                                  +----------+ | |             | |
  ||                                               | +-------------+ |
  |+-----------------------------------------------+                 |
  |                                                                  |
  +------------------------------------------------------------------+

            Figure 4: Illustration of CAdES-C format

 NOTE 1: The complete certificate and revocation references are added 
         to the CAdES-T as an unsigned attribute.

 NOTE 2: As a minimum, the signer will provide the CAdES-BES or when 
         indicating that the signature conforms to an explicit signing 
         policy the CAdES-EPES.

 NOTE 3: To reduce the risk of repudiating signature creation, the 
         trusted time indication needs to be as close as possible to 
         the time the signature was created.  The signer or a TSP could 
         provide the CAdES-T, if not the verifier should create the 
         CAdES-T on first receipt of an electronic signature because 
         the CAdES-T provides independent evidence of the existence of 
         the signature prior to the trusted time indication.

 NOTE 4: An CAdES-T trusted time indications must be created before a 
         certificate has been revoked or expired.

 NOTE 5: The signer and TSP could provide the CAdES-C, to minimize 
         this risk and when the signer does not provide the CAdES-C, 
         the verifier should create the CAdES-C when the required 
         component of revocation and validation data become available, 
         this may require a grace period.

 NOTE 6: A grace period permits certificate revocation information to 
         propagate through the revocation processes.  This period could 
         extend from the time an authorized entity requests certificate 
         revocation, to when the information is available for the 
         relying to use.  In order to make sure that the certificate 
         was not revoked at the time the signature was time-marked or 


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         time-stamped, verifiers should wait until the end of the grace 
         period.  A signature policy may define specific values for 
         grace periods.  An illustration of a grace period is provided 
         in figure 5.


                +<--------------Grace Period --------->+
    ----+-------+-------+--------+---------------------+----------+
        ^       ^       ^        ^                     ^          ^
        |       |       |        |                     |          |
        |       |       |        |                     |          |
    Signature   |     First      |                   Second       |
     creation   |   revocation   |                  revocation    |
      time      |     status     |                    status      |
                |    checking    |                  checking      |
                |                |                                |
            Time-stamp      Certification                       Build
               or              path                            CAdES-C
            time-mark      construction
              over          & verification
            signature


                Figure 5: Illustration of a grace period
Figure 5: Illustration of a grace period

 NOTE 7: CWA 14171 (see informative references) specifies a signature 
         validation process using CAdES-T, CAdES-C and a grace period. 
         Annex B provides example validation processes.  Clause C.4 
         provides additional information about applying grace periods 
         during the validation process.

The verifier's conformance requirements are defined in clause 8.3 for 
time stamped CAdES-C and clause 8.4 for time marked CAdES-C.  The 
present document only defines conformance requirements for the verifier 
up to an ES with complete validation data (CAdES-C).  This means that 
none of the extended and archive forms of Electronic Signature as 
defined in clauses 4.4.3 to 4.4.4) need to be implemented to achieve 
conformance to the present document.

4.4.3 Extended electronic signature formats

CAdES-C can be extended by adding unsigned attributes to the electronic 
signature.  The present document defines various unsigned attributes 
that are applicable for very long term verification, and for preventing 
some disaster situations which are discussed in annex C.  Annex B 
provides the details of the various extended formats, all the required 
unsigned attributes for each type and how they can be used within the 
electronic signature validation process.  The clauses below give an 
overview of the various forms of extended signature formats in the 
present document.



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4.4.3.1 EXtended Long Electronic Signature (CAdES-X Long)

Extended Long format (CAdES-X Long) in accordance with the present 
document adds to the CAdES-C format the certificate-values and 
revocation-values attributes.  The first one contains the whole 
certificate path required for verifying the signature; the second one 
the CRLs and/OCSP responses required for the validation of the 
signature.  This provides a know repository of certificate and 
revocation information required to validate an CAdES-C and prevents 
such information getting lost.  Clauses 6.3.3 and 6.3.4 give 
specification details.  Clause B.1.1 gives details on the production of 
the format.  Clauses C4.1 to C.4.2 provide the rationale.

The structure of the CAdES-X Long format is illustrated in figure 6.


  +----------------------- CAdES-X-Long -----------------------------+
  |+------------------------------------ CadES-C --+                 |
  ||                                  +----------+ | +-------------+ |
  ||+------ CAdES -------------------+|Timestamp | | |             | |
  |||                                ||  over    | | | Complete    | |
  |||+---------++----------+         ||digital   | | | certificate | |
  ||||Signer's ||  Signed  | Digital ||signature | | |     and     | |
  ||||Document ||Attributes|Signature||          | | | revocation  | |
  ||||         ||          |         ||Optional  | | |    data     | |
  |||+---------++----------+         ||when      | | |             | |
  ||+--------------------------------+|timemarked| | |             | |
  ||                                  +----------+ | |             | |
  ||                               +-------------+ | +-------------+ |
  ||                               | Complete    | |                 |
  ||                               | certificate | |                 |
  ||                               | and         | |                 |
  ||                               | revocation  | |                 |
  ||                               | references  | |                 |
  ||                               +-------------+ |                 |
  |+-----------------------------------------------+                 |
  |                                                                  |
  +------------------------------------------------------------------+

                 Figure 6: Illustration of CAdES-X-Long


4.4.3.2 EXtended Electronic Signature with Time Type 1 
        (CAdES-X Type 1)

Extended format with time type 1 (CAdES-X Type 1) in accordance with 
the present document adds to the CAdES-C format the CAdES-C-time-stamp 
attribute, whose content is a time-stamp token on the CAdES-C itself.  

This provides an integrity and trusted time protection over all the 
elements and references.  It may protect the certificates, CRLs and 
OCSP responses in case of a later compromise of a CA key, CRL key or 
OCSP issuer key.  Clause 6.3.5 provides the specification details.  

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Clause B.1.2 gives details on the production of the time-stamping 
process.  Clauses C.4.4.1 provides the rationale.  

The structure of the CAdES-X Type 1 format is illustrated in figure 7.



+----------------------- CAdES-X-Type 1 -----------------------------+
|+-------------------------------------- CAdES-C --+                 |
||                                    +----------+ | +-------------+ |
||+--------- CAdES ------------------+|Timestamp | | |             | |
|||                                  ||over      | | |             | |
|||+---------++----------++---------+||digital   | | |             | |
||||Signer's ||  Signed  || Digital |||signature | | | Timestamp   | |
||||Document ||Attributes||Signature|||          | | |   over      | |
||||         ||          ||         |||Optional  | | | CAdES-C     | |
|||+---------++----------++---------+||when      | | |             | |
||+----------------------------------+|timemarked| | |             | |
||                                    +----------+ | |             | |
||                                 +-------------+ | +-------------+ |
||                                 | Complete    | |                 |
||                                 | certificate | |                 |
||                                 | and         | |                 |
||                                 | revocation  | |                 |
||                                 | references  | |                 |
||                                 +-------------+ |                 |
|+-------------------------------------------------+                 |
|                                                                    |
+--------------------------------------------------------------------+

                Figure 7: Illustration of  CAdES-X Type  1


4.4.3.3 EXtended Electronic Signature with Time Type 2
        (CAdES-X Type 2)

Extended format with time type 2 (CAdES-X Type 2) in accordance with 
the present document adds to the CAdES-C format the CAdES-C-time-
stamped-certs-crls-references attribute, whose content is a time-stamp 
token on the certification path and revocation information references. 
This provides an integrity and trusted time protection over all the 
references. 

It may protect the certificates, CRLs and OCSP responses in case of a 
later compromise of a CA key, CRL key or OCSP issuer key.






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Both CAdES-X Type 1 and CAdES-X Type 2 counter the same threats and the 
usage of one or the other depends on the environment.  Clause 6.3.5 
provides the specification details.  Clause B.1.3 gives details on the 
production of the time-stamping process.  Clause C.4.4.2 provides the 
rationale.

The structure of the CAdES-X Type 2 format is illustrated in figure 8.


+------------------------- CAdES-X-Type 2 ---------------------------+
|+-----------------------------------------CAdES-C --+               |
||                                      +-----------+|               |
||+----- CAdES ------------------------+| Timmestamp||               |
|||                                    || over      ||               |
|||+---------+ +----------+ +---------+|| digital   ||+-------------+|
||||Signer's | |  Signed  | | Digital ||| signature ||| Time-stamp  ||
||||Document | |Attributes| |signature|||           ||| only over   ||
||||         | |          | |         ||| optional  ||| complete    ||
|||+---------+ +----------+ +---------+|| when      ||| certificate ||
||+------------------------------------+| timemarked|||    and      ||
||                                      +-----------+|| revocation  ||
||                                    +-------------+|| references  ||
||                                    | Complete    ||+-------------+|
||                                    | certificate ||               |
||                                    | and         ||               |
||                                    | revocation  ||               |
||                                    | references  ||               |
||                                    +-------------+|               |
|+---------------------------------------------------+               |
|                                                                    |
+--------------------------------------------------------------------+

                  Figure 8: Illustration of CAdES-X Type 2



4.4.3.4 EXtended Long Electronic Signature with Time (CAdES-X Long Type 
1 or 2)

Extended Long with Time (CAdES-X Long Type 1 or 2) in accordance with 
the present document is a combination of CAdES-X Long and one of the 
two former types (CAdES-X Type 1 and CAdES-X Type 2).  Clause B.1.4 
gives details on the production of the time-stamping process.  Clause 
C4.8 in annex C provides the rationale.

The structure of the CAdES-X Long Type 1 and CAdES-X Long Type 2. 
format is illustrated in figure 9.





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 +------------------ CAdES-X Long Type 1 or 2 -----------------------+
 |                                                   +--------------+|
 |+-------------------------------------- CAdES-C --+|+------------+||
 ||                                                 ||| Timestamp  |||
 ||+------- CAdES --------------------++----------+ |||   over     |||
 |||                                  ||Timestamp | |||  CAdES-C   |||
 |||                                  ||over      | ||+------------+||
 |||+---------++----------++---------+||digital   | ||      OR      ||
 ||||Signer's ||  Signed  || Digital |||signature | ||+------------+||
 ||||Document ||Attributes||signature|||          | ||| Timestamp  |||
 ||||         ||          ||         |||Optional  | ||| only over  |||
 |||+---------++----------++---------+||when      | ||| complete   |||
 ||+----------------------------------+|timemarked| ||| certificate|||
 ||                                    +----------+ |||    and     |||
 ||                                                 ||| Revocation |||
 ||                                 +-------------+ ||| References |||
 ||                                 | Complete    | ||+------------+||
 ||                                 | certificate | |+--------------+|
 ||                                 | and         | | +------------+ |
 ||                                 | revocation  | | | Complete   | |
 ||                                 | references  | | |certificate | |
 ||                                 +-------------+ | |   and      | |
 |+-------------------------------------------------+ |revocation  | |
 |                                                    |  value     | |
 |                                                    +------------+ |
 +-------------------------------------------------------------------+

   Figure 9: Illustration of CAdES-X Long Type 1 and CAdES Long Type 2


4.4.4 Archival Electronic Signature (CAdES-A)

Archival Form (CAdES-A) in accordance with the present document builds 
on a CAdES-X Long or a CAdES-X Long Type 1 or 2 by adding one or more 
archive-time-stamp attributes.  This form is used for archival of long-
term signatures.  Successive time-stamps protect the whole material 
against vulnerable hashing algorithms or the breaking of the 
cryptographic material or algorithms.  Clause 6.4 contains the 
specification details.  Clauses C.4.5 and C.4.8 provide the rationale.

The structure of the CAdES-A form is illustrated in figure 10.










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+---------------------------CAdES-A ---------------------------------+
|+----------------------------------------------------+              |
||                                    +--------------+| +----------+ |
||+----------------------CAdES-C ----+|+------------+|| |          | |
|||                     +----------+ ||| Timestamp  ||| |          | |
|||+---- CAdES-BES ----+|Timestamp | |||    over    ||| |          | |
||||    or CAdeS-EPES  ||  over    | |||   CAdES-C  ||| |  Archive | |
||||                   ||digital   | ||+------------+|| |          | |
||||                   ||signature | ||      or      || |Timestamp | |
||||                   ||          | ||+------------+|| |          | |
||||                   ||Optional  | ||| Timestamp  ||| |          | |
||||                   ||when      | ||| only over  ||| |          | |
||||                   ||Timemarked| ||| complete   ||| |          | |
|||+-------------------+|          | ||| certificate||| +----------+ |
|||                     +----------+ |||    and     |||              |
|||                  +-------------+ ||| revocation |||              |
|||                  | Complete    | ||| references |||              |
|||                  | certificate | ||+------------+||              |
|||                  | and         | |+--------------+|              |
|||                  | revocation  | | +------------+ |              |
|||                  | references  | | |  Complete  | |              |
|||                  +-------------+ | |certificate | |              |
|||                                  | |    and     | |              |
||+----------------------------------+ |revocation  | |              |
||                                     |  values    | |              |
||                                     +------------+ |              |
|+----------------------------------------------------+              |
+--------------------------------------------------------------------+

                   Figure 10: Illustration of CAdES-A


      TABLE NOTE : Timestamps are timestamp token that may themselves 
      include unsigned attributes required to validate the timestamp 
      token, such as the complete-certificate-references and 
      complete-revocation-references attributes as defined by the 
      present document.

4.5 Arbitration

The CAdES-C may be used for arbitration should there be a dispute 
between the signer and verifier, provided that:

   - the arbitrator knows where to retrieve the signer's certificate 
     (if not already present), all the cross-certificates and the 
     required CRLs, ACRLs or OCSP responses referenced in the CAdES-C;

   - when time-stamping in the CAdES-T is being used, the certificate 
     from the TSU that has issued the time-stamp token in the CAdES-T 
     format is still within its validity period;


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   - when time-stamping in the CAdES-T is being used, the certificate 
     from the TSU that has issued the time-stamp token in the CAdES-T 
     format is not revoked at the time of arbitration;

   - when time-marking in the CAdES-T is being used, a reliable audit 
     trail from the Time-Marking Authority is available for 
     examination regarding the time;

   - none of the private keys corresponding to the certificates used 
     to verify the signature chain have ever been compromised;

   - the cryptography used at the time the CAdES-C was built has not 
     been broken at the time the arbitration is performed;

   - If the signature policy can be explicit or implicitly identified 
     then an arbitrator is able to determine the rules required to 
     validate the electronic signature.

4.6 Validation process

The Validation Process validates an electronic signature, the output 
status of the validation process can be:

   - invalid;

   - incomplete validation;

   - valid.

An Invalid response indicates that either the signature format is 
incorrect or that the digital signature value fails verification (e.g. 
the integrity check on the digital signature value fails or any of the 
certificates on which the digital signature verification depends is 
known to be invalid or revoked).

An Incomplete Validation response indicates that the signature 
validation status is currently unknown.  In the case of incomplete 
validation, additional information may be made available to the 
application or user, thus allowing them to decide what to do with the 
electronic signature.  In the case of incomplete validation, the 
electronic signature may be checked again at some later time when 
additional information becomes available.

 NOTE: For example; an incomplete validation may be because all the 
       required certificates are not available or the grace period is 
       not completed.

A Valid response indicates that the signature has passed verification 
and it complies with the signature validation policy.




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Example validation sequences are illustrated in annex B.


5 Electronic signature attributes

This clause builds upon the existing Cryptographic Message Syntax 
(CMS), as defined in RFC 3852 [4], and Enhanced Security Services 
(ESS), as defined in RFC 2634 [5].  The overall structure of Electronic 
Signature is as defined in CMS.  The Electronic Signature (ES) uses 
attributes defined in CMS, ESS and the present document.  The present 
document defines ES attributes which it uses and are not defined 
elsewhere.

The mandated set of attributes and the digital signature value is 
defined as the minimum Electronic Signature (ES) required by the 
present document.  A signature policy MAY mandate that other signed 
attributes are present.

5.1 General syntax

The general syntax of the ES is as defined in CMS (RFC 3852 [4]).

 NOTE: CMS defines content types for id-data, id-signedData, id-
       envelopedData, id-digestedData, id-encryptedData, and id-
       authenticatedData.  Although CMS permits other documents to 
       define other content types, the ASN.1 type defined should not 
       be a CHOICE type.  The present document does not define other 
       content types.

5.2 Data content type 

The data content type of the ES is as defined in CMS (RFC 3852 [4]).

 NOTE: Requirements to identify encoding types within the content when 
       the ContentType set to id-data are outside the scope of the 
       present document, see annex F for an example of using MIME to 
       identify encoding type. 

5.3 Signed-data content type

The signed-data content type of the ES is as defined in CMS (RFC 3852 
[4]).

To make sure that the verifier uses the right signer's key, the present 
document mandates that an unambiguous reference of the signer's 
certificate is always included in the Signing Certificate signed 
attribute (see clause 5.7.3).








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5.4 SignedData type

The syntax of the SignedData of the ES is as defined in CMS (RFC 3852 
[4]).

The fields of type SignedData have the meanings as defined in CMS (RFC 
3852 [4]) except that:

   - the syntax version number value shall be 3.

The identification of signer's certificate used to create the signature 
is always signed (see clause 5.7.3).  The validation policy may specify 
requirements for the presence of certain certificates.
The degenerate case where there are no signers is not valid in the 
present document.

5.5 EncapsulatedContentInfo type

The syntax of the EncapsulatedContentInfo type ES is as defined in CMS 
(RFC 3852 [4]).

For the purpose of long term validation as defined by the present 
document, it is advisable that either the eContent is present, or the 
data which is signed is archived in such as way as to preserve any data 
encoding.  It is important that the OCTET STRING used to generate the 
signature remains the same every time either the verifier or an 
arbitrator validates the signature.

 NOTE:  The eContent is optional in CMS, this allows the signed data 
        to be encapsulated in the SignData (i.e. Signature + data) 
        alternatively the signed data may be absent form the SignData 
        (i.e. Signature only).  It is in the case of signature only 
        that the data which is signed needs to be archived in such as 
        way as to preserve any data encoding.
The degenerate case where there are no signers is not valid in the 
present document.

5.6 SignerInfo type

The syntax of the SignerInfo type ES is as defined in CMS (RFC 3852 
[4]).

Per-signer information is represented in the type SignerInfo.  In the 
case of multiple independent signatures (see clause B.5), there is an 
instance of this field for each signer.

The fields of type SignerInfo have the meanings defined in CMS (RFC 
3852 [4]) except that the signedAttrs field shall contain the following 
attributes:





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   - content-type as defined in clause 5.7.1;
   - message-digest as defined in clause 5.7.2;
   - signing-certificate as defined in clause 5.7.3.

5.6.1 Message digest calculation process

The message digest calculation process is as defined in CMS (RFC 3852 
[4]).

5.6.2 Message signature generation process

The input to the message signature generation process is as defined in 
CMS (RFC 3852 [4]).

5.6.3 Message signature verification process

The procedures for message signature verification are defined in CMS 
(RFC 3852 [4]) and enhanced in the present document.
The input to the signature verification process includes the signer's 
public key which SHALL be verified as correct using the signing 
certificate reference attribute containing a reference to the signing 
certificate.

5.7 Basic ES mandatory present attributes

The following attributes SHALL be present with the signed-data defined 
by the present document.  The attributes are defined in CMS (RFC 3852 
[4]).

5.7.1 Content type

The syntax of the content-type attribute type of the ES is as defined 
in CMS (RFC 3852 [4]).

5.7.2 Message digest

The syntax of the message-digest attribute type of the ES is as defined 
in CMS (RFC 3852 [4]).

5.7.3 Signing certificate reference attributes

The Signing certificate reference attributes are supported by using 
either the ESS signing-certificate attribute or the other-signing-
certificate attribute.

These attributes shall contain a reference to the signer's certificate, 
they are designed to prevent the simple substitution and re-issue 
attacks and to allow for a restricted set of certificates to be used in 
verifying a signature.  They have a compact form (much shorter than the 
full certificate) that allows to a certificate to be unambiguously 
identified.




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One, and only one, of the following alternative attributes SHALL be 
present with the signedData defined by the present document.

   - The ESS signing-certificate attribute, which is adopted in 
     existing standards, may be used if the SHA-1 hashing algorithm is 
     used.

   - The other-signing-certificate attribute shall be used when other 
     hashing algorithms are to be utilized.

The certificate to be used to verify the signature shall be identified 
in the sequence (i.e. the certificate from the signer) and the sequence 
shall not be empty. The signature validation policy may mandate other 
certificates be present that may include all the certificates up to the 
point of trust.

5.7.3.1 ESS signing certificate attribute definition

The syntax of the signing-certificate attribute type of the ES is as 
defined in Enhanced Security Services (ESS), RFC 2634 [5] and further 
qualified in the present document.

The sequence of policy information field is not used in the present 
document.

The ESS signing-certificate attribute shall be a signed attribute.
The encoding of the ESSCertID for this certificate shall include the 
issuerSerial field.

The issuerAndSerialNumber present in the SignerInfo shall be consistent 
with issuerSerial field.  The certificate identified shall be used 
during the signature verification process.  If the hash of the 
certificate does not match the certificate used to verify the 
signature, the signature shall be considered invalid.

 NOTE: Where an attribute certificate is used by the signer to 
       associate a role, or other attributes of the signer, with the 
       electronic signature this is placed in the signer-attributes 
       attribute as defined in clause 5.8.3.

5.7.3.2 Other signing certificate attribute definition

The following attribute is identical to the ESS signing-certificate 
defined above except that this attribute can be used with hashing 
algorithms other than SHA-1.

This attribute shall be used in the same manner as defined above for 
the ESS signing-certificate attribute.
The following object identifier identifies the other-signing-
certificate attribute:




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id-aa-ets-otherSigCert OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-aa(2) 19 }

The other-signing-certificate attribute value has the ASN.1 syntax 
OtherSigningCertificate:

OtherSigningCertificate ::=  SEQUENCE {
    certs        SEQUENCE OF OtherCertID,
    policies     SEQUENCE OF PolicyInformation OPTIONAL
                 -- NOT USED IN THE PRESENT DOCUMENT }

OtherCertID ::= SEQUENCE {
    otherCertHash            OtherHash,
    issuerSerial             IssuerSerial OPTIONAL }

OtherHash ::= CHOICE {
    sha1Hash OtherHashValue,  -- This contains a SHA-1 hash
    otherHash OtherHashAlgAndValue}

OtherHashValue ::= OCTET STRING

OtherHashAlgAndValue ::= SEQUENCE {
    HashAlgorithm     AlgorithmIdentifier,
    HashValue         OtherHashValue }

5.8 Additional mandatory attributes for Explicit Policy-based 
Electronic Signatures

5.8.1 Signature policy identifier

he present document mandates that for CAdES-EPES a reference to the 
signature policy is included in the signedData.  This reference is 
explicitly identified.  A signature policy defines the rules for 
creation and validation of an electronic signature, is included as a 
signed attribute with every Explicit Policy-based Electronic Signature. 
The signature-policy-identifier shall be a signed attribute.

The following object identifier identifies signature-policy-identifier 
attribute:

id-aa-ets-sigPolicyId OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-aa(2) 15 }

signature-policy-identifier attribute values have ASN.1 type 
SignaturePolicyIdentifier:
SignaturePolicyIdentifier ::=CHOICE{
        signaturePolicyId          SignaturePolicyId,
        signaturePolicyImplied     SignaturePolicyImplied
                                   -- not used in this version}



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SignaturePolicyId ::= SEQUENCE {
        sigPolicyId           SigPolicyId,
        sigPolicyHash         SigPolicyHash OPTIONAL,
        sigPolicyQualifiers   SEQUENCE SIZE (1..MAX) OF 
                                SigPolicyQualifierInfo OPTIONAL}

SignaturePolicyImplied ::= NULL

The sigPolicyId field contains an object-identifier which uniquely 
identifies a specific version of the signature policy.  The syntax of 
this field is as follows:

SigPolicyId ::= OBJECT IDENTIFIER

The sigPolicyHash field optionally contains the identifier of the hash 
algorithm and the hash of the value of the signature policy.

If the signature policy is defined using ASN.1, then the hash is 
calculated on the value without the outer type and length fields and 
the hashing algorithm shall be as specified in the field sigPolicyHash.

If the signature policy is defined using another structure, the type of 
structure and the hashing algorithm shall be either specified as part 
of the signature policy, or indicated using a signature policy 
qualifier.

SigPolicyHash ::= OtherHashAlgAndValue

 NOTE: In the previous version of TS 101 733 (i.e. version 1.5.1) 
       sigPolicyHash was mandatory.  Implementations requiring to be 
       backward compatible with version 1.5.1 and previous versions 
       of the current document MUST include SigPolicyHash.

A signature policy identifier may be qualified with other information 
about the qualifier.  The semantics and syntax of the qualifier is as 
associated with the object-identifier in the sigPolicyQualifierId 
field.  The general syntax of this qualifier is as follows:

SigPolicyQualifierInfo ::= SEQUENCE {
        sigPolicyQualifierId  SigPolicyQualifierId,
        sigQualifier          ANY DEFINED BY sigPolicyQualifierId }

The present document specifies the following qualifiers:

   - spuri: this contains the web URI or URL reference to the 
     signature policy;

   - sp-user-notice: this contains a user notice which should be 
     displayed whenever the signature is validated.




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sigpolicyQualifierIds defined in the present document

SigPolicyQualifierId ::=
        OBJECT IDENTIFIER 

    id-spq-ets-uri OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-spq(5) 1 }

SPuri ::= IA5String

    id-spq-ets-unotice OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-spq(5) 2 }

SPUserNotice ::= SEQUENCE {
        noticeRef        NoticeReference OPTIONAL,
        explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {
        organization     DisplayText,
        noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {
        visibleString    VisibleString  (SIZE (1..200)),
        bmpString        BMPString      (SIZE (1..200)),
        utf8String       UTF8String     (SIZE (1..200)) }

5.9 CMS imported optional attributes

The following attributes MAY be present with the signed-data, the 
attributes are defined in CMS (RFC 3852 [4]) and are imported into the 
present document.  Were appropriated the attributes are qualified and 
profiled by the present document.

5.9.1 Signing time

The signing-time attribute specifies the time at which the signer 
claims to have performed the signing process.

Signing-time attribute values for ES have the ASN.1 type SigningTime as 
defined in CMS (RFC 3852 [4]).  This type is further qualified in the 
present document.

The present document recommends the use of GeneralizedTime.

5.9.2 Countersignature

The counterSignature attribute values for ES have ASN.1 type 
CounterSignature as defined in CMS (RFC 3852 [4]).




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A counterSignature attribute shall be an unsigned attribute.

5.10 ESS imported optional attributes

The following attributes MAY be present with the signed-data defined by 
the present document.  The attributes are defined in ESS and are 
imported into the present document and were appropriate qualified and 
profiled by the present document.

5.10.1 Content reference attribute 

The content-reference attribute is a link from one SignedData to 
another.  It may be used to link a reply to the original message to 
which it refers, or to incorporate by reference one SignedData into 
another.  The content-reference attribute shall be a signed attribute.

Content-reference attribute values for ES have ASN.1 type 
ContentReference as defined in ESS (RFC 2634 [5]).

The content-reference attribute shall be used as defined in ESS (RFC 
2634 [5]) and further qualified in the present document.

5.10.2 Content identifier attribute 

The content-identifier attribute provides an identifier for the signed 
content for use when reference may be later required to that content, 
for example in the content reference attribute in other signed data 
sent later.  The content-identifier shall be a signed attribute.

content-identifier attribute type values for of the ES have ASN.1 type 
ContentIdentifier as defined in ESS (RFC 2634 [5]).

The minimal content-identifier attribute should contain a concatenation 
of user-specific identification information (such as a user name or 
public keying material identification information), a GeneralizedTime 
string, and a random number.

5.10.3 Content hints attribute 

The content-hints attribute provides information that describes the 
format of the signed content.  It may be used by the signer to indicate 
to a verifier a precise presentation format of the signed data (e.g. 
text, voice, and video).  This attribute SHOULD be present when the 
signed data is to be presented to human users on verification if the 
presentation format is not implicit within the data that has been 
signed.

The syntax of the content-hints attribute type of the ES as defined in 
ESS (RFC 2634 [5]).




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When used to indicate the precise format of the data to be presented to 
the user the following rules apply:

   - the contentType indicates the type of the associated content.  It 
     is an object identifier (i.e. a unique string of integers) 
     assigned by an authority that defines the content type;

   - when the contentType is id-data the contentDescription shall 
     define the presentation format, the format may be defined by MIME 
     types.

When the format of the content is defined by MIME types the following 
rules apply:

   - the contentType shall be id-data as defined in CMS (RFC 3852 
     [4]);

   - the contentDescription shall be used to indicate the encoding of 
     the data in accordance with the rules defined RFC 2045 [6], see 
     annex F for an example structured contents and MIME.

 NOTE 1: id-data OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) 
         rsadsi(113549) pkcs(1) pkcs7(7) 1 }

 NOTE 2: contentDescription is optional in ESS (RFC 2634 [5]).  It may 
         be used to complement contentTypes defined elsewhere , such 
         definitions are outside the scope of the present document.

5.11 Additional optional attributes defined in the present document

This clause defines a number of attributes that may be used to meet 
specific requirements.

5.11.1 Commitment type indication attribute

There may be situations where a signer wants to explicitly indicate to 
a verifier that by signing the data, it illustrates a type of 
commitment on behalf of the signer.  The commitment-type-indication 
attribute conveys such information.

The commitment-type-indication attribute shall be a signed attribute.
The commitment type may be:

   - defined as part of the signature policy, in which case the 
     commitment type has precise semantics that is defined as part of 
     the signature policy;

   - be a registered type, in which case the commitment type has 
     precise semantics defined by registration, under the rules of the 
     registration authority.  Such a registration authority may be a 
     trading association or a legislative authority.


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The signature policy specifies a set of attributes that it 
"recognizes".  This "recognized" set includes all those commitment 
types defined as part of the signature policy as well as any externally 
defined commitment types that the policy may choose to recognize.  Only 
recognized commitment types are allowed in this field.

The following object identifier identifies the commitment-type-
indication attribute:

id-aa-ets-commitmentType OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 16}

commitment-type-indication attribute values have ASN.1 type 
CommitmentTypeIndication.

CommitmentTypeIndication ::= SEQUENCE {
  commitmentTypeId CommitmentTypeIdentifier,
  commitmentTypeQualifier SEQUENCE SIZE (1..MAX) OF
                 CommitmentTypeQualifier OPTIONAL}

CommitmentTypeIdentifier ::= OBJECT IDENTIFIER

CommitmentTypeQualifier ::= SEQUENCE {
   commitmentTypeIdentifier   CommitmentTypeIdentifier,
   qualifier                  ANY DEFINED BY commitmentTypeIdentifier }

The use of any qualifiers to the commitment type is outside the scope 
of the present document.

The following generic commitment types are defined in the present 
document:

id-cti-ets-proofOfOrigin OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 1}

id-cti-ets-proofOfReceipt OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 2}

id-cti-ets-proofOfDelivery OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 3}

id-cti-ets-proofOfSender OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 4}

id-cti-ets-proofOfApproval OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 5}

id-cti-ets-proofOfCreation OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 6}




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These generic commitment types have the following meaning:

Proof of origin indicates that the signer recognizes to have created, 
approved and sent the message.

Proof of receipt indicates that signer recognizes to have received the 
content of the message.

Proof of delivery indicates that the TSP providing that indication has 
delivered a message in a local store accessible to the recipient of the 
message.

Proof of sender indicates that the entity providing that indication has 
sent the message (but not necessarily created it).

Proof of approval indicates that the signer has approved the content of 
the message.

Proof of creation indicates that the signer has created the message 
(but not necessarily approved, nor sent it).

5.11.2 Signer location attribute

The signer-location attribute specifies a mnemonic for an address 
associated with the signer at a particular geographical (e.g. city) 
location.  The mnemonic is registered in the country in which the 
signer is located and is used in the provision of the Public Telegram 
Service (according to ITU-T Recommendation F.1 [11]).

The signer-location attribute shall be a signed attribute.
The following object identifier identifies the signer-location 
attribute:

id-aa-ets-signerLocation OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 17}

Signer-location attribute values have ASN.1 type SignerLocation:
SignerLocation ::= SEQUENCE { -- at least one of the following shall be 
present

      countryName    [0]    DirectoryString OPTIONAL, 
                            -- As used to name a Country in X.500 
      localityName   [1]    DirectoryString OPTIONAL, 
                            -- As used to name a locality in X.500 
      postalAdddress [2]    PostalAddress OPTIONAL }

PostalAddress ::= SEQUENCE SIZE(1..6) OF DirectoryString






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5.11.3 Signer attributes attribute

The signer-attributes attribute specifies additional attributes of the 
signer (e.g. role).

It may be either:

   - claimed attributes of the signer;

   - certified attributes of the signer.

The signer-attributes attribute shall be a signed attribute.
The following object identifier identifies the signer-attribute 
attribute:

id-aa-ets-signerAttr OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 18}

signer-attributes values have ASN.1 type SignerAttribute:
SignerAttribute ::= SEQUENCE OF CHOICE {
    ClaimedAttributes     [0]   ClaimedAttributes,
    certifiedAttributes   [1]   CertifiedAttributes }

ClaimedAttributes ::= SEQUENCE OF Attribute 

CertifiedAttributes ::= AttributeCertificate  
-- as defined in RFC 3281 : see clause 4.1.

 NOTE 1: Only a single signer-attributes can be used

 NOTE 2: The claimedAttributes and certifiedAttributes fields are as 
         defined in ITU-T Recommendations X.501 [9] and X.509 [1].

5.11.4 Content time-stamp

The content-time-stamp attribute is an attribute which is the time-
stamp token of the signed data content before it is signed. 
The content-time-stamp attribute shall be a signed attribute.

The following object identifier identifies the content-time-stamp 
attribute:

id-aa-ets-contentTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 20}

Content-time-stamp attribute values have ASN.1 type ContentTimestamp:
ContentTimestamp::= TimeStampToken







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The value of messageImprint of TimeStampToken (as described in RFC 3161 
[7]) shall be a hash of the value of eContent field within 
encapContentInfo in the signedData.

For further information and definition of TimeStampToken see 
clause 7.4.

 NOTE: Content-time-stamp indicates that the signed information was 
       formed before the date included in the Content-time-stamp.

5.12 Support for multiple signatures

5.12.1 Independent signatures

Multiple independent signatures (see clause B.5) are supported by 
independent SignerInfo from each signer.

Each SignerInfo shall include all the attributes required under the 
present document and shall be processed independently by the verifier.

5.12.2 Embedded signatures

Multiple embedded signatures (see clause C.5) are supported using the 
countersignature unsigned attribute (see clause 7.1).  Each counter 
signature is carried in Countersignature held as an unsigned attribute 
to the SignerInfo to which the counter-signature is applied.

6 Additional Electronic Signature validation attributes

This clause specifies attributes that contain different types of 
validation data.  These attributes build on the electronic signature 
specified in clause 5.  This includes:

   - Signature-time-stamp applied to the electronic signature value or 
     a Time-Mark in an audit trail.  This is defined as the Electronic 
     Signature with Time (CAdES-T);

   - complete validation data references which comprises the time-
     stamp of the signature value (CAdES-T), plus references to all 
     the certificates (complete-certificate-references) and revocation 
     (complete-revocation-references) information used for full 
     validation of the electronic signature.  This is defined as the 
     Electronic Signature with Complete data references (CAdES-C).

 NOTE 1: Formats for CAdES-T are illustrated in clause 4.4 and the 
         attribute are defined in clause 6.1.1.







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 NOTE 2: Formats for CAdES-C are illustrated in clause 4.4.  The 
         required attributes for the CAdES-C signature format are 
         defined in clause 6.2.1 to 6.2.2, optional attributes are 
         defined in clauses 6.2.3 and 6.2.4.

In addition the following optional eXtended forms of validation data 
are also defined, see annex B for an overview the eXtended forms of 
validation data:

   - CAdES-X with time stamp: there are two types of time-stamp used 
     in extended validation data defined by the present document:

        - Type 1(CAdES-X Type 1): comprises a time-stamp over the ES 
          with complete validation data (CAdES-C);

        - Type 2 (CAdES-X Type2): comprises a time-stamp over the 
          certification path references and the revocation information 
          references used to support the CAdES-C.

 NOTE 3: Formats for CAdES-X Type 1 and CAdES-X Type 2 are illustrated 
         in clauses B.1.2 and B.1.3 respectively.

   - CAdES-X Long :comprises the complete validation data references 
     (CAdES-C) plus the actual values of all the certificates and 
     revocation information used in the CAdES-C.

 NOTE 4: Formats for CAdES-X Long are illustrated in clause B.1.1.

   - CAdES-X Long Type 1 or CAdES-X Long Type 2: comprises an X-Time-
     Stamp (Type 1 or Type 2) plus the actual values of all the 
     certificates and revocation information used in the CAdES-C as 
     per CAdES-X Long.

This clause also specifies the data structures used in Archive 
validation data format (CAdES-A)of eXtended forms: 

   - Archive form of electronic signature (CAdES-A) comprises the 
     complete validation data references (CAdES-C), the certificate 
     and revocation values (as in a CAdES-X Long ), if present any 
     existing extended electronic signature timestamps (CAdES-X Type 1 
     or CAdES-X Type 2), plus the signed user data and an additional 
     archive time-stamp applied over all that data.  An archive time-
     stamp may be repeatedly applied after long periods to maintain 
     validity when electronic signature and time-stamping algorithms 
     weaken.

The additional data required to create the forms of electronic 
signature identified above is carried as unsigned attributes associated 
with an individual signature by being placed in the unsignedAttrs field 
of SignerInfo .  Thus all the attributes defined in clause 6 are 
unsigned attributes.



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 NOTE 5: Where multiple signatures are to be supported, as described 
         in clause 5.12, each signature has a separate SignerInfo. 
         Thus, each signature requires its own unsigned attribute 
         values to create CAdES-T, CAdES-C, etc.

 NOTE 6: the optional attributes of the extended validation data are 
         defined in clauses 6.3 and 6.4.

6.1 Electronic Signature Time-stamped (CAdES-T)

An Electronic Signature with time-stamp is an electronic signature for 
which part, but not all, of the additional data required for validation 
is available (i.e. some certificates and revocation information are 
available but not all).

The minimum structure time-stamp validation data is:

   - the Signature Time-stamp Attribute as defined in clause 6.1.1 
     over the ES signature value.

6.1.1 Signature time- stamp attribute definition

The signature-time-stamp attribute is a TimeStampToken computed on the 
signature value for a specific signer.  It is an unsigned attribute.  
Several instances of this attribute may occur with an electronic 
signature, from different TSAs.

The following object identifier identifies the signature-time-stamp 
attribute:

id-aa-signatureTimeStampToken OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 14}

The signature-time-stamp attribute value has ASN.1 type 
SignatureTimeStampToken:
SignatureTimeStampToken ::= TimeStampToken

The value of messageImprint field within TimeStampToken shall be a hash 
of the value of the signature field within SignerInfo for the 
signedData being time-stamped.

For further information and definition of TimeStampToken see 
clause 7.4.

 NOTE 1: In the case of multiple signatures it is possible to have a 
         TimeStampToken computed for each and all signers, or 
         TimeStampToken computed on one signer's signature and no 
         TimeStampToken on another signer's signature.





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 NOTE 2: In the case of multiple signatures, several TSTs , issued by 
         different TSAs, may be present within the same signerInfo (see 
         RFC 3852 [4]).

6.2 Complete validation reference data (CAdES-C)

An electronic signature with complete validation data references 
(CAdES-C) is an Electronic Signature for which all the additional data 
required for validation (i.e. all certificates and revocation 
information) is available.  This form is built on the CAdES-T form 
defined above.

As a minimum the complete validation data shall include the following:

   - a time, which shall either be a signature-timestamp attribute, as 
     defined in clause 6.1.1, or a time mark operated by a Time-
     Marking Authority;

   - complete-certificate-references, as defined in clause 6.2.1;

   - complete-revocation-references , as defined in clause 6.2.2.

6.2.1 Complete certificate references attribute definition

The complete-certificate-references attribute is an unsigned attribute.  
It references the full set of CA certificates that have been used to 
validate an ES with Complete validation data up to (but not including) 
the signer's certificate.  Only a single instance of this attribute 
shall occur with an electronic signature.

 NOTE 1: The signer's certificate is referenced in the signing 
         certificate attribute (see clause 5.7.3).

id-aa-ets-certificateRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 21}

The complete-certificate-references attribute value has the ASN.1 
syntax CompleteCertificateRefs.

CompleteCertificateRefs ::=  SEQUENCE OF OtherCertID

OtherCertID is defined in clause 5.7.3.2.

The IssuerSerial that shall be present in OtherCertID.  The certHash 
shall match the hash of the certificate referenced.

 NOTE 2: Copies of the certificate values may be held using the 
         certificate-values attribute defined in clause 6.3.3.





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         This attribute MAY include references to the certification 
         chain for any TSUs that provides time-stamp tokens.  In this 
         case the unsigned attribute shall be added to the signData of 
         the relevant times tamp token as an unsignedAttrs in the 
         signerInfos field.

6.2.2 Complete Revocation References attribute definition

The complete-revocation-references attribute is an unsigned attribute.  
Only a single instance of this attribute shall occur with an electronic 
signature.  It references the full set of the CRL, ACRL or OCSP 
responses that have been used in the validation of the signer and CA 
certificates used in ES with Complete validation data.

This attribute can be used to illustrate that the verifies has taken 
due diligence of the available revocation information and then to be 
able to retrieve that information when stored elsewhere.
The following object identifier identifies the complete-revocation-
references attribute:

id-aa-ets-revocationRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 22}

The complete-revocation-references attribute value has the ASN.1 syntax 
CompleteRevocationRefs

CompleteRevocationRefs ::=  SEQUENCE OF CrlOcspRef

CrlOcspRef ::= SEQUENCE {
   Crlids      [0]   CRLListID    OPTIONAL,
   Ocspids     [1]   OcspListID   OPTIONAL,
   OtherRev    [2]   OtherRevRefs OPTIONAL
}

CompleteRevocationRefs shall contain one CrlOcspRef for the signing-
certificate, followed by one for each OtherCertID in the 
CompleteCertificateRefs attribute.  The second and subsequent 
CrlOcspRef fields shall be in the same order as the OtherCertID to 
which they relate.  At least one of CRLListID or OcspListID or 
OtherRevRefs should be present for all but the "trusted" CA of the 
certificate path.

CRLListID ::=  SEQUENCE {
    crls        SEQUENCE OF CrlValidatedID}

CrlValidatedID ::=  SEQUENCE {
     crlHash                   OtherHash, 
     crlIdentifier             CrlIdentifier OPTIONAL}






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CrlIdentifier ::= SEQUENCE {
    crlissuer                 Name,
    crlIssuedTime             UTCTime,
    crlNumber                 INTEGER OPTIONAL
}

OcspListID ::=  SEQUENCE {
    ocspResponses        SEQUENCE OF OcspResponsesID}

OcspResponsesID ::=  SEQUENCE {
    ocspIdentifier              OcspIdentifier,
    ocspRepHash                 OtherHash    OPTIONAL
}

OcspIdentifier ::= SEQUENCE {
   OcspResponderID    ResponderID,      -- As in OCSP response data
   ProducedAt         GeneralizedTime   -- As in OCSP response data
}

When creating a crlValidatedID, the crlHash is computed over the entire 
DER encoded CRL including the signature.  The crlIdentifier would 
normally be present unless the CRL can be inferred from other 
information.

The crlIdentifier is to identify the CRL using the issuer name and the 
CRL issued time, which shall correspond to the time thisUpdate 
contained in the issued CRL, and if present, the crlNumber.  The 
crlListID attribute is an unsigned attribute.  In the case that the 
identified CRL is a Delta CRL then references to the set of CRLs to 
provide a complete revocation list shall be included.

The OcspIdentifier is to identify the OCSP response using the issuer 
name and the time of issue of the OCSP response which shall correspond 
to the time producedAt contained in the issued OCSP response.  Since it 
may be needed to make the difference between two OCSP responses 
received within the same second, then the hash of the response 
contained in the OcspResponsesID may be needed to solve the ambiguity.

 NOTE: Copies of the CRL and OCSP responses values may be held using 
       the revocation-values attribute defined in clause 6.3.4.

OtherRevRefs ::= SEQUENCE {
   OtherRevRefType    OtherRevRefType,
   OtherRevRefs       ANY DEFINED BY otherRevRefType
 }

OtherRevRefType ::= OBJECT IDENTIFIER





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The syntax and semantics of other revocation references is outside the 
scope of the present document.  The definition of the syntax of the 
other form of revocation information is as identified by 
OtherRevRefType.
This attribute MAY include the references to the full set of the CRL, 
ACRL or OCSP responses that have been used to verify the certification 
chain for any TSUs that provides time-stamp tokens.  In this case the 
unsigned attribute shall be added to the signData of the relevant 
timestamp token as an unsignedAttrs in the signerInfos field.

6.2.3 Attribute certificate references attribute definition

This attribute is only used when an user attribute certificate is 
present in the electronic signature.

The attribute-certificate-references attribute is an unsigned 
attribute.  It references the full set of AA certificates that have 
been used to validate the attribute certificate.  Only a single 
instance of this attribute shall occur with an electronic signature.

id-aa-ets-attrCertificateRefs OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 44}

The attribute-certificate-references attribute value has the ASN.1 
syntax AttributeCertificateRefs.

AttributeCertificateRefs ::=  SEQUENCE OF OtherCertID

OtherCertID is defined in clause 5.8.2.

 NOTE: Copies of the certificate values may be held using the 
       certificate-values attribute defined in clause 6.3.3.

6.2.4 Attribute revocation references attribute definition

This attribute is only used when a user attribute certificate is 
present in the electronic signature and when that attribute certificate 
can be revoked.

The attribute-revocation-references attribute is an unsigned attribute.  
Only a single instance of this attribute shall occur with an electronic 
signature.  It references the full set of the ACRL or OCSP responses 
that have been used in the validation of the attribute certificate.   
This attribute can be used to illustrate that the verifier has taken 
due diligence of the available revocation information.

The following object identifier identifies the attribute-revocation-
references attribute:






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id-aa-ets-attrRevocationRefs OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 45}

The attribute-revocation-references attribute value has the ASN.1 
syntax AttributeRevocationRefs.
AttributeRevocationRefs ::=  SEQUENCE OF CrlOcspRef

6.3 Extended validation data (CAdES-X)

This clause specifies a number of optional attributes that are used by 
extended forms of electronic signatures (see annex B for an overview 
these forms of validation data).

6.3.1 Time-stamped validation data (CAdES-X Type 1 or Type 2)

The extended validation data MAY include one of the following 
additional attributes, forming a CAdES-X Time-Stamp validation data 
(CAdES-X Type 1 or CAdES-X Type 2), to provide additional protection 
against later CA compromise and provide integrity of the validation 
data used:

   - CAdES-C Time-stamp, as defined in clause 6.3.5 (CAdES-X Type 1); 
     or

   - Time-Stamped Certificates and CRLs references, as defined in 
     clause 6.3.6 (CAdES-X Type 2).

6.3.2 Long validation data (CAdES-X Long, CAdES-X Long Type 1 or 2)

The extended validation data MAY also include the following additional 
information, forming a CAdES-X Long, for use if later validation 
processes may not have access to this information:

   - certificate-values as defined in clause 6.3.3;
   - revocation-values as defined in clause 6.3.4.

The extended validation data MAY in addition to certificate-values and 
revocation-values as defined in clauses 6.3.3 and 6.3.4 include one of 
the following additional attributes, forming an CAdES-X Long Type 1 or 
CAdES-X Long Type 2.

   - CAdES-C Time-stamp, as defined in clause 6.3.3 (CAdES-X long Type 
     1); or

   - Time-Stamped Certificates and CRLs references, as defined in 
     clause 6.3.4 (CAdES-X Long Type 2).







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The CAdES-X Long Type 1 or CAdES-X Long Type 2 provide additional 
protection against later CA compromise and provide integrity of the 
validation data used.

 NOTE 1: The CAdES-X Long provides long term proof of a valid 
         electronic signature as long as the CAs are trusted such that 
         these keys cannot be compromised or the cryptography used 
         broken.
 NOTE 2: As long as the time stamp data remains valid, the CAdES-X 
         Long Type 1 and the CAdES-X Long Type 2 provides the following 
         important property for long standing signatures; that having 
         been found once to be valid, it shall continue to be so months 
         or years later, long after the validity period of the 
         certificates have expired, or after the user key has been 
         compromised.

6.3.3 Certificate values attribute definition

This attribute MAY be used to contain the certificate information 
required for the following forms of eXtended Electronic Signature: 
CAdES-X Long , ES X-Long Type 1 and CAdES-X Long Type 2, see clause 
B.1.1 for an illustration of this form of electronic signature.

The certificate-values attribute is an unsigned attribute.  Only a 
single instance of this attribute shall occur with an electronic 
signature.  It holds the values of certificates referenced in the 
complete-certificate-references attribute.

 NOTE: If an attribute certificate is used, it is not provided in this 
       structure but shall be provided by the signer as a signer-
       attributes attribute (see clause 5.11.3).

The following object identifier identifies the certificate-values 
attribute:

id-aa-ets-certValues OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 23}

The certificate-values attribute value has the ASN.1 syntax 
CertificateValues

CertificateValues ::=  SEQUENCE OF Certificate

Certificate is defined in clause 7.1 (which is as defined in ITU-T 
Recommendation X.509 [1]).

This attribute MAY include the certification information for any TSUs 
that have provided the time-stamp tokens if these certificates are not 
already included in the TSTs as part of the TSUs signatures.  In this 
case the unsigned attribute shall be added to the signData of the 
relevant timestamp token.



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6.3.4 Revocation values attribute definition

This attribute is used to contain the revocation information required 
for the following forms of eXtended Electronic Signature: CAdES-X Long, 
ES X-Long Type 1 and CAdES-X Long Type 2, see clause B.1.1 for an 
illustration of this form of electronic signature.

The revocation-values attribute is an unsigned attribute.  Only a 
single instance of this attribute shall occur with an electronic 
signature.  It holds the values of CRLs and OCSP referenced in the 
complete-revocation-references attribute.

The following object identifier identifies the revocation-values 
attribute:

id-aa-ets-revocationValues OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 24}

The revocation-values attribute value has the ASN.1 syntax 
RevocationValues

RevocationValues ::=  SEQUENCE {
   crlVals          [0] SEQUENCE OF CertificateList OPTIONAL,
   ocspVals         [1] SEQUENCE OF BasicOCSPResponse OPTIONAL,
   otherRevVals     [2] OtherRevVals OPTIONAL}

OtherRevVals ::= SEQUENCE {
   OtherRevValType   OtherRevValType,
   OtherRevVals      ANY DEFINED BY OtherRevValType
 }

OtherRevValType ::= OBJECT IDENTIFIER

The syntax and semantics of the other revocation values (OtherRevVals) 
is outside the scope of the present document.  The definition of the 
syntax of the other form of revocation information is as identified by 
OtherRevRefType.

CertificateList is defined in clause 7.2 (which as defined in ITU-T 
Recommendation X.509 [1]).

BasicOCSPResponse is defined in clause 7.3 (which as defined in RFC 
2560 [3]).

This attribute MAY include the values of revocation data including CRLs 
and OCSP for any TSUs that have provided the time-stamp tokens if these 
certificates are not already included in the TSTs as part of the TSUs 
signatures.  In this case the unsigned attribute shall be added to the 
signData of the relevant timestamp token.



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6.3.5 CAdES-C time-stamp attribute definition

This attribute is used to protect against CA key compromise.
This attribute is used for the time stamping the complete electronic 
signature (CAdES-C).  It is used in the following forms of eXtended 
Electronic Signature; CAdES-X Type 1 and CAdES-X Long Type 1, see 
clause B.1.2 for an illustration of this form of electronic signature.

The CAdES-C-timestamp attribute is an unsigned attribute.  It is a 
time-stamp token of the hash of the electronic signature and the 
complete validation data (CAdES-C).  It is a special purpose 
TimeStampToken Attribute which time-stamps the CAdES-C.  Several 
instances of this attribute may occur with an electronic signature from 
different TSAs.

The following object identifier identifies the CAdES-C-Timestamp 
attribute:

id-aa-ets-escTimeStamp OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 25}

The CAdES-C-timestamp attribute value has the ASN.1 syntax 
ESCTimeStampToken.

ESCTimeStampToken ::= TimeStampToken

The value of messageImprint field within TimeStampToken shall be a hash 
of the concatenated values (without the type or length encoding for 
that value) of the following data objects:

   - OCTETSTRING of the SignatureValue field within SignerInfo;

   - signature-time-stamp; or a time mark operated by a Time-Marking 
     Authority;

   - complete-certificate-references s attribute;

   - complete-revocation-references attribute.

For further information and definition of the TimeStampToken see 
clause 7.4.

6.3.6 Time-stamped certificates and crls references attribute 
definition 

This attribute is used to protect against CA key compromise.

This attribute is used for the time stamping certificate and revocation 
references.  It is used in the following forms of eXtended Electronic 
Signature; CAdES-X Type 2 and CAdES-X Long Type 2, see clause B.1.3 for 
an illustration of this form of electronic signature.



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A time-stamped-certs-crls-references attribute is an unsigned 
attribute.  It is a time-stamp token issued for a list of referenced 
certificates and OCSP responses/CRLs to protect against certain CA 
compromises.  Its syntax is as follows:

The following object identifier identifies the time-stamped-certs-crls-
references attribute:

id-aa-ets-certCRLTimestamp OBJECT IDENTIFIER ::= { iso(1) member
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 26}
The attribute value has the ASN.1 syntax TimestampedCertsCRLs.

TimestampedCertsCRLs ::= TimeStampToken

The value of messageImprint field within TimeStampToken shall be a hash 
of the concatenated values (without the type or length encoding for 
that value) of the following data objects as present in the ES with 
Complete validation data:

   - complete-certificate-references attribute;
   - complete-revocation-references attribute.

6.4 Archive validation data

Where an electronic signature is required to last for a very long time, 
and a the time-stamp token on an electronic signature is in danger of 
being invalidated due to algorithm weakness or limits in the validity 
period of the TSA certificate, then it may be required to time-stamp 
the electronic signature several times.  When this is required an 
archive time-stamp attribute may be required for the archive form of 
electronic signature (CAdES-A).  This archive time-stamp attribute may 
be repeatedly applied over a period of time.

6.4.1 Archive time-stamp attribute definition

The archive-time-stamp attribute is a time-stamp token of many of the 
elements of the signedData in the electronic signature.  If the 
certificate-values and revocation-values attributes are not present in 
the CAdES-BES or CAdES-EPES, then they shall be added to the electronic 
signature prior to computing the archive time-stamp token.  The 
archive-time-stamp attribute is an unsigned attribute.  Several 
instances of this attribute may occur with an electronic signature both 
over time and from different TSUs.

The following object identifier identifies the nested archive-time-
stamp attribute:

id-aa-ets-archiveTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 27}



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Archive-time-stamp attribute values have the ASN.1 syntax 
ArchiveTimeStampToken

ArchiveTimeStampToken ::= TimeStampToken

The value of messageImprint field within TimeStampToken shall be a hash 
of the concatenation of:

   - The encapContentInfo element of the SignedData sequence;

   - When present, the Certificates and crls elements of the 
     SignedData sequence;

   - Together with all data elements in the SignerInfo sequence 
     including all signed and unsigned attributes.

 NOTE 1: The SignedData definition is the following:

SignedData ::= SEQUENCE {
        version CMSVersion,
        digestAlgorithms DigestAlgorithmIdentifiers,
        encapContentInfo EncapsulatedContentInfo,
        certificates [0] IMPLICIT CertificateSet OPTIONAL,
        crls [1] IMPLICIT CertificateRevocationLists OPTIONAL,
        signerInfos SignerInfos }

 NOTE 2: SignerInfo definition is as follows:

SignerInfo ::= SEQUENCE {
        version CMSVersion,
        sid SignerIdentifier,
        digestAlgorithm DigestAlgorithmIdentifier,
        signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL,
        signatureAlgorithm SignatureAlgorithmIdentifier,
        signature SignatureValue,
        unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }

Further information and definition of TimeStampToken see clause 7.4.
The timestamp should be created using stronger algorithms (or longer 
key lengths) than in the original electronic signatures and weak 
algorithm (key length) timestamps.

 NOTE 3: This form of ES also provides protection against a TSP key 
         Compromise. 

The ArchiveTimeStamp will be added as an unsigned attribute in the 
SignerInfo sequence.  For the validation of one ArchiveTimeStamp the 
data elements of the SignerInfo must be concatenated excluding all 
later ArchivTimeStampToken attributes.




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Certificates and revocation information required to validate the 
ArchiveTimeStampshall be provided by one of the following methods:

   - The TSU provides the information in the SignedData of the 
     timestamp token;

   - Adding the complete-certificate-references attribute and the 
     complete-revocation-references attribute of the TSP as an 
     unsigned attribute within TimeStampToken, when the required 
     information is store elsewhere;

   - Adding the certificate-values attribute and the revocation-values 
     attribute of the TSP as an unsigned attribute within 
     TimeStampToken, when the required information is store elsewhere.

7 Other standard data structures

7.1 Public-key certificate format

The X.509 v3 certificate basis syntax is defined in ITU-T 
Recommendation X.509 [1].  A profile of the X.509 v3 certificate is 
defined in RFC 3280 [2], which is being revised.  The reader should 
consult the latest version of this RFC or any RFC that makes it 
obsolete.

7.2 Certificate revocation list format

The X.509 v2 CRL syntax is defined in ITU-T Recommendation X.509 [1].  
A profile of the X.509 v2 CRL is defined in RFC 3280 [2], which is 
being revised.

7.3 OCSP response format

The format of an OCSP token is defined in RFC 2560 [3].

7.4 Time-stamp token format

The format of a TimeStampToken type is defined in RFC 3161 [7] and TS 
101 861 (see informative references).

7.5 Name and attribute formats

The syntax of the naming and other attributes is defined in ITU-T 
Recommendation X.509 [1].

The name used by the signer, held as the subject in the signer's 
certificate, shall be allocated and verified on registration with the 
Certification Authority, either directly or indirectly through a 
Registration Authority, before being issued with a Certificate.




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The present document places no restrictions on the form of the name.  
The subject's name may be a distinguished name, as defined in ITU-T 
Recommendation X.500 [12], held in the subject field of the 
certificate, or any other name form held in the subjectAltName 
certificate extension field as defined in ITU-T Recommendation X.509 
[1].  In the case that the subject has no distinguished name, the 
subject name can be an empty sequence and the subjectAltName extension 
shall be critical.

All TSP name forms (Certification Authorities, Attribute Authorities 
and Time Stamping Authorities) shall be in the form of a distinguished 
name held in the subject field of the certificate.

The TSP name form shall include identifiers for the organization 
providing the service and the legal jurisdiction (e.g. country) under 
which it operates.

Where a signer signs as an individual but wishes to also identify 
him/herself as acting on behalf of an organization, it may be necessary 
to provide two independent forms of identification.  The first 
identity, with is directly associated with the signing key identifies 
him/her as an individual.  The second, which is managed independently, 
identifies that person acting as part of the organization, possibly 
with a given role.

In this case one of the two identities is carried in the 
subject/subjectAltName field of the signer's certificate as described 
above.

The present document does not specify the format of signer's attribute 
that may be included in public key certificates.

 NOTE : Signer's attribute may be supported by using a claimed role in 
        the CMS signed attributes field or by placing an attribute 
        certificate containing a certified role in the CMS signed 
        attributes field, see clause 7.6.

7.6 Attribute certificate

The syntax of the AttributeCertificate type is defined in RFC 3281 [13].

8. Conformance requirements

The present document defines conformance requirements for the 
generation of two forms of basic electronic signature, one of the two 
forms must be implemented.

The present document defines conformance requirements for the 
verification of two forms of basic electronic signature, one of the two 
forms must be implemented.




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The present document only defines conformance requirements up to an ES 
with Complete validation data (CAdES-C).  This means that none of the 
extended and archive forms of Electronic Signature (CAdES-X, CAdES-A) 
need to be implemented to get conformance to the present document.

On verification the inclusion of optional signed and unsigned 
attributes must be supported only to the extended that the signature is 
verifiable.  The semantics of optional attributes may be unsupported, 
unless specified otherwise by a signature policy.

8.1 CAdES-Basic Electronic Signature (CAdES-BES)

A system supporting CAdES-BES signers according to the present document 
shall, at a minimum, support generation of an electronic signature 
consisting of the following components:

   - The general CMS syntax and content type as defined in RFC 3852 
     [4] (see clauses 5.1 and 5.2);

   - CMS SignedData as defined in RFC 3852 [4] with version set to 3 
     and at least one SignerInfo shall be present (see clauses 5.3 to 
     5.6);

   - The following CMS attributes as defined in RFC 3852 [4]:

       - content-type; this shall always be present (see clause 5.7.1);

       - message-digest; this shall always be present (see 
         clause 5.7.2).

   - One of following attributes as defined in the present document:

       - signing-certificate: as defined in clause 5.7.3.1;
       - Other-Signing-Certificate as defined in clause 5.7.3.2.

8.2 CAdES-Explicit Policy-based Electronic Signature

A system supporting Policy-based signers according to the present 
document shall, at a minimum, support generation of an electronic 
signature consisting of the previous components defined for the basic 
signer, plus:

   - The following attributes as defined in clause 5.9:

       - signature-policy-identifier; this shall always be present (see 
         clause 5.8.1).

8.3 Verification using time-stamping

A system supporting verifiers according to the present document with 
time-stamping facilities shall, at a minimum, support:

   - verification of the mandated components of an electronic 
     signature, as defined in clause 8.1.

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   - signature-time-stamp attribute, as defined in clause 6.1.1.

   - complete-certificate-references, attribute as defined in 
     clause 6.2.1.

   - complete-revocation-references attribute, as defined in 
     clause 6.2.2.

   - Public Key Certificates, as defined in ITU-T Recommendation X.509 
     [1] (see clause 8.1).

   - either of:

        - Certificate Revocation Lists.  as defined in ITU-T 
          Recommendation X.509 [1] (see clause 8.2); or

        - on-line Certificate Status Protocol, as defined in RFC 2560 
          [3] (see clause 8.3).

8.4 Verification using secure records

A system supporting verifiers according to the present document shall, 
at a minimum, support:

   - verification of the mandated components of an electronic 
     signature, as defined in clause 8.1;

   - complete-certificate-references attribute, as defined in 
     clause 6.2.1;

   - complete-revocation-references attribute, as defined in 
     clause 6.2.2;

   - a record must be maintained and cannot be undetectable modified, 
     of the electronic signature and the time when the signature was 
     first validated using the referenced certificates and revocation 
     information;

   - Public Key Certificates, as defined in ITU-T Recommendation X.509 
     [1] (see clause 8.1);

   - either of:

       - Certificate Revocation Lists.  as defined in ITU-T 
         Recommendation X.509 [1] (see clause 8.2); or

       - on-line Certificate Status Protocol, as defined in RFC 2560 
         [3] (see clause 8.3).




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9. Security considerations

9.1 Protection of private key

The security of the electronic signature mechanism defined in the 
present document depends on the privacy of the signer's private key.  
Implementations should take steps to ensure that private keys cannot be 
compromised.

9.2 Choice of algorithms

Implementers should be aware that cryptographic algorithms become 
weaker with time.  As new cryptoanalysis techniques are developed and 
computing performance improves, the work factor to break a particular 
cryptographic algorithm will reduce.  Therefore, cryptographic 
algorithm implementations should be modular allowing new algorithms to 
be readily inserted.  That is, implementers should be prepared for the 
set of mandatory to implement algorithms to change over time.

10. IANA Considerations

Not applicable

11. References

11.1 Normative references

    [1]   ITU-T Recommendation X.509 (2000)/ISO/IEC 9594-8 (2001): 
          "Information technology - Open Systems Interconnection - 
          The Directory: Authentication framework".

    [2]   IETF RFC 3280 (2002): "Internet X.509 Public Key 
          Infrastructure Certificate and Certificate Revocation List 
          (CRL) Profile".

    [3]   IETF RFC 2560 (1999): "X.509 Internet Public Key 
          Infrastructure Online Certificate Status Protocol - OCSP".

    [4]   IETF RFC 3852 (2004): "Cryptographic Message Syntax (CMS)".

    [5]   IETF RFC 2634 (1999): "Enhanced Security Services for 
          S/MIME".

    [6]   IETF RFC 2045 (1996): "Multipurpose Internet Mail Extensions 
          (MIME) Part One: Format of Internet Message Bodies".

    [7]   IETF RFC 3161 (2001): "Internet X.509 Public Key 
          Infrastructure Time-Stamp Protocol (TSP)".

    [8]   ITU-T Recommendation X.680 (1997): "Information technology - 
          Abstract Syntax Notation One (ASN.1): Specification of basic 
          notation".

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    [9]   ITU-T Recommendation X.501 (2000)/ISO/IEC 9594-1 (2001): 
          "Information technology - Open Systems Interconnection - 
          Directory models ".

   [10]   IETF RFC 3370 (2002): "Cryptographic Message Syntax (CMS) 
          Algorithms".

   [11]   ITU-T Recommendation F.1: "Operational provisions for the 
          international public telegram service".

   [12]   ITU-T Recommendation X.500: "Information technology - Open 
          Systems Interconnection - The Directory: Overview of 
          concepts, models and services".

   [13]   IETF RFC 3281 (2002): "An Internet Attribute Certificate 
          Profile for Authorization".

   [14]   ITU-T Recommendation X.208 (1988): "Specification of Abstract
          Syntax Notation One (ASN.1)".


Referenced documents hereabove which are not found to be publicly 
available in the expected location might be found at 
http://docbox.etsi.org/Reference.

   [STDWORDS] IETF RFC 2119 Bradner, S., "Key words for use in RFCs to 
              Indicate Requirement Levels", BCP 14, RFC 2

11.2 Informative references

   Directive 1999/93/EC of the European Parliament and of the Council
   of 13 December 1999 on a Community framework for electronic 
   signatures.

   ETSI Standard TS 101 733 V.1.6.3 (2005-06) Electronic Signature 
   Formats.  Note: copies of ETSI TS 101 733 can be freely downloaded 
   from the ETSI web site www.etsi.org.

   IETF RFC 2246 (1999): "The TLS Protocol Version 1.0".

   IETF RFC 2437 (1998): "PKCS #1: RSA Cryptography Specifications 
   Version 2.0".

   IETF RFC 2479 (1998): "Independent Data Unit Protection Generic 
   Security Service Application Program Interface (IDUP-GSS-API)".

   IETF RFC 2510 (1999): "Internet X.509 Public Key Infrastructure 
   Certificate Management Protocols".




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   IETF RFC 2587 (1999): "Internet X.509 Public Key Infrastructure 
   LDAPv2 Schema".

   IETF RFC 3125 (2000): "Electronic Signature Policies".

   IETF RFC 2559 (2003): "Internet X.509 Public Key Infrastructure 
   Operational Protocols - LDAPv2".

   ETSI TS 101 861: "Time stamping profile".

   ETSI TS 101 903: "XML Advanced Electronic Signatures (XAdES)".

   ETSI TS 102 023: "Electronic Signatures and Infrastructures (ESI); 
   Policy requirements for time-stamping authorities".

   ETSI TS 102 038: "Electronic Signatures and Infrastructures (ESI);
   XML format for signature policies".

   ETSI TR 102 272.  "Electronic Signatures and Infrastructures (ESI); 
   ASN.1 format for signature policies".

   ISO 7498-2 (1989): "Information processing systems - Open Systems 
   Interconnection - Basic Reference Model - Part 2: Security 
   Architecture".

   ISO/IEC 13888-1 (2004): "IT security techniques - Non-repudiation - 
   Part 1: General".

   ISO/IEC 9796-2 (2002): "Information technology - Security techniques 
   - Digital signature schemes giving message recovery - Part 2:
   Integer factorization based mechanisms".

   ISO/IEC 9796-4 (1998): "Digital signature schemes giving message 
   recovery - Part 4: Discrete logarithm based mechanisms".

   ISO/IEC 10118-1 (2000): "Information technology - Security 
   techniques - Hash-functions - Part 1: General".

   ISO/IEC 10118-2 (2000): "Information technology - Security 
   techniques - Hash-functions - Part 2: Hash-functions using an n-bit 
   block cipher algorithm".

   ISO/IEC 10118-3 (2004): "Information technology - Security 
   techniques - Hash-functions - Part 3: Dedicated hash-functions".

   ISO/IEC 10118-4 (1998): "Information technology - Security 
   techniques - Hash-functions - Part 4: Hash-functions using modular 
   arithmetic".

   ISO/IEC 14888-1 (1998): "Information technology - Security 
   techniques - Digital signatures with appendix - Part 1: General". 



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   ISO/IEC 14888-2 (1999): "Information technology - Security 
   techniques - Digital signatures with appendix - Part 2: Identity-
   based mechanisms".

   ISO/IEC 14888-3 (1998): "Information technology - Security 
   techniques - Digital signatures with appendix - Part 3: Certificate-
   based mechanisms".

   ISO/IEC 15946-2 (2002): "Information technology - Security 
   techniques - Cryptographic techniques based on elliptic curves - 
   Part 2: Digital signatures".

   ISO/IEC 15946-3 (2002): "Information technology - Security 
   techniques - Cryptographic techniques based on elliptic curves -
   Part 3: Key establishment".

   ISO/IEC 10181-5:  Security Frameworks in Open Systems.
   Non-Repudiation Framework.  April 1997.

   ITU-T Recommendation X.690 (2002): "Specification of basic encoding 
   rules for Abstract Syntax Notation One (ASN.1)".

   CWA 14171 CEN Workshop Agreements: "General Guidelines for 
   Electronic Signature Verification".

   XMLDSIG: W3C/IETF Recommendation (February 2002): "XML-Signature 
   Syntax and Processing".

   ANSI X9.30-1 (1997): "Public Key Cryptography for the Financial 
   Services Industry - Part 1: The Digital Signature Algorithm (DSA)".

   ANSI X9.30-2 (1997): "Public Key Cryptography for the Financial 
   Services Industry - Part 2: The Secure Hash Algorithm (SHA-1)".

   ANSI X9.31-1 (1997): "Public Key Cryptography Using Reversible 
   Algorithms for the Financial Services Industry - 
   Part 1: The RSA Signature Algorithm".

   ANSI X9.31-2 (1996): "Public Key Cryptography Using Reversible 
   Algorithms for the Financial Services Industry - 
   Part 2: Hash Algorithms".

   ANSI X9.62 (1998): "Public Key Cryptography for the Financial 
   Services Industry - The Elliptic Curve Digital Signature Algorithm 
   (ECDSA)".

   IEEE P1363 (2000): "Standard Specifications for Public-Key 
   Cryptography".




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12. Authors' addresses

      Denis Pinkas
      Bull S.A. 
      Rue Jean-Jaures 
      78340 Les Clayes sous Bois CEDEX
      FRANCE

      EMail: Denis.Pinkas@bull.net

      Nick Pope
      Security & Standards
      192 Moulsham Street
      Chelmsford, Essex
      CM2 0LG
      United Kingdom

      EMail: pope@secstan.com

      John Ross
      Security & Standards
      192 Moulsham Street
      Chelmsford, Essex
      CM2 0LG
      United Kingdom

      EMail: ross@secstan.com

This Informational RFC has been produced in ETSI TC-ESI.

      ETSI
      F-06921 Sophia Antipolis, Cedex - FRANCE
      650 Route des Lucioles - Sophia Antipolis
      Valbonne - France
      Tel: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16
      secretariat@etsi.fr
      http://www.etsi.org
















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Annex A (normative): ASN.1 definitions

This annex provides a summary of all the ASN.1 syntax definitions for 
new syntax defined in the present document.

A.1 Signature format definitions using X.208 ASN.1 syntax

 NOTE: The ASN.1 module defined in clause A.1 using syntax defined in 
       ITU-T Recommendation X.208 [14] has precedence over that 
       defined in clause A.2 in the case of any conflict.

ETS-ElectronicSignatureFormats-ExplicitSyntax88 { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-mod(0) 
eSignature-explicit88(28)}

DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS All 

IMPORTS 

-- Cryptographic Message Syntax (CMS): RFC 3852

   ContentInfo, ContentType, id-data, id-signedData, SignedData, 
   EncapsulatedContentInfo, SignerInfo, id-contentType, 
   id-messageDigest, MessageDigest, id-signingTime, SigningTime,
   id-countersignature, Countersignature
      FROM CryptographicMessageSyntax2004
      { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
      smime(16) modules(0) cms-2004(24) }


-- ESS Defined attributes: RFC 2634 (Enhanced Security Services 
-- for S/MIME)

   id-aa-signingCertificate, SigningCertificate, IssuerSerial,
   id-aa-contentReference, ContentReference, id-aa-contentIdentifier,
   ContentIdentifier
      FROM ExtendedSecurityServices
      { iso(1) member-body(2) us(840) rsadsi(113549) 
       pkcs(1) pkcs-9(9) smime(16) modules(0) ess(2) }

-- Internet X.509 Public Key Infrastructure - Certificate and CRL 
-- Profile: RFC 3280 

   Certificate, AlgorithmIdentifier, CertificateList, Name,
   DirectoryString, Attribute, BMPString, UTF8String
      FROM PKIX1Explicit88 
      {iso(1) identified-organization(3) dod(6) internet(1) 
      security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit(18)}



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   GeneralNames, GeneralName, PolicyInformation
      FROM PKIX1Implicit88
      {iso(1) identified-organization(3) dod(6) internet(1) security(5)
       mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit (19)}

-- Internet Attribute Certificate Profile for Authorization - RFC 3281

   AttributeCertificate
      FROM PKIXAttributeCertificate {iso(1) identified-organization(3) 
                dod(6) internet(1) security(5) mechanisms(5) pkix(7) 
                id-mod(0) id-mod-attribute-cert(12)}

-- OCSP - RFC 2560

   BasicOCSPResponse, ResponderID
      FROM OCSP {iso(1) identified-organization(3) dod(6) internet(1)
      security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-ocsp(14)}

-- Time Stamp Protocol RFC 3161

   TimeStampToken
      FROM PKIXTSP
      {iso(1) identified-organization(3) dod(6) internet(1) security(5) 
      mechanisms(5) pkix(7) id-mod(0) id-mod-tsp(13)};

-- S/MIME Object Identifier arcs used in the present document 
-- ==========================================================

-- S/MIME  OID arc used in the present document
-- id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
-- us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 16 }

-- S/MIME Arcs
-- id-mod  OBJECT IDENTIFIER ::= { id-smime 0 }
-- modules
-- id-ct   OBJECT IDENTIFIER ::= { id-smime 1 }
-- content types
-- id-aa   OBJECT IDENTIFIER ::= { id-smime 2 }
-- attributes
-- id-spq  OBJECT IDENTIFIER ::= { id-smime 5 }
-- signature policy qualifier
-- id-cti  OBJECT IDENTIFIER ::= { id-smime 6 }
-- commitment type identifier

-- Definitions of Object Identifier arcs used in the present document
-- ==================================================================

-- The allocation of OIDs to specific objects are given below with 
-- the associated ASN.1 syntax definition

-- OID used referencing electronic signature mechanisms based on 
-- the present document for use with the IDUP API (see annex D)



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   id-etsi-es-IDUP-Mechanism-v1 OBJECT IDENTIFIER ::=
   { itu-t(0) identified-organization(4) etsi(0) 
     electronic-signature-standard (1733) part1 (1) idupMechanism (4) 
     etsiESv1(1) }

-- Basic ES CMS Attributes Defined in the present document
-- =======================================================

-- Mandatory RFC 3852 Electronic Signature Attributes

-- OtherSigningCertificate

    id-aa-ets-otherSigCert OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-aa(2) 19 }

   OtherSigningCertificate ::=  SEQUENCE {
      certs        SEQUENCE OF OtherCertID,
      policies     SEQUENCE OF PolicyInformation OPTIONAL
                   -- NOT USED IN THE PRESENT DOCUMENT
   }

   OtherCertID ::= SEQUENCE {
      otherCertHash            OtherHash,
      issuerSerial             IssuerSerial OPTIONAL }

   OtherHash ::= CHOICE {
       sha1Hash     OtherHashValue,  -- This contains a SHA-1 hash
       otherHash    OtherHashAlgAndValue}

   OtherHashValue ::= OCTET STRING

   OtherHashAlgAndValue ::= SEQUENCE {
      hashAlgorithm   AlgorithmIdentifier,
      hashValue       OtherHashValue }

-- Policy ES Attributes Defined in the present document
-- ====================================================

-- Mandatory Basic Electronic Signature Attributes as above, 
-- plus in addition.


-- Signature Policy Identifier

   id-aa-ets-sigPolicyId OBJECT IDENTIFIER ::= { iso(1)
   member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
   smime(16) id-aa(2) 15 }





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   SignaturePolicy ::= CHOICE {
      signaturePolicyId          SignaturePolicyId,
      signaturePolicyImplied     SignaturePolicyImplied 
                                 --  not used in this version
   }

   SignaturePolicyId ::= SEQUENCE {
      sigPolicyId        SigPolicyId,
      sigPolicyHash      SigPolicyHash OPTIONAL,
      sigPolicyQualifiers   SEQUENCE SIZE (1..MAX) OF
                                   SigPolicyQualifierInfo OPTIONAL
   }
 
   SignaturePolicyImplied ::= NULL

   SigPolicyId ::= OBJECT IDENTIFIER

   SigPolicyHash ::= OtherHashAlgAndValue

   SigPolicyQualifierInfo ::= SEQUENCE {
      sigPolicyQualifierId  SigPolicyQualifierId,
      sigQualifier          ANY DEFINED BY sigPolicyQualifierId }

   SigPolicyQualifierId ::=   OBJECT IDENTIFIER 

   id-spq-ets-uri OBJECT IDENTIFIER ::= { iso(1)
   member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
   smime(16) id-spq(5) 1 }

   SPuri ::= IA5String

   id-spq-ets-unotice OBJECT IDENTIFIER ::= { iso(1)
   member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
   smime(16) id-spq(5) 2 }

   SPUserNotice ::= SEQUENCE {
       noticeRef        NoticeReference OPTIONAL,
       explicitText     DisplayText OPTIONAL}

   NoticeReference ::= SEQUENCE {
      organization     DisplayText,
      noticeNumbers    SEQUENCE OF INTEGER }

   DisplayText ::= CHOICE {
      visibleString    VisibleString  (SIZE (1..200)),
      bmpString        BMPString      (SIZE (1..200)),
      utf8String       UTF8String     (SIZE (1..200)) }






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-- Optional Electronic Signature Attributes

-- Commitment Type

id-aa-ets-commitmentType OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 16}


   CommitmentTypeIndication ::= SEQUENCE {
     commitmentTypeId CommitmentTypeIdentifier,
     commitmentTypeQualifier SEQUENCE SIZE (1..MAX) OF
            CommitmentTypeQualifier OPTIONAL}

   CommitmentTypeIdentifier ::= OBJECT IDENTIFIER

   CommitmentTypeQualifier ::= SEQUENCE {
      commitmentTypeIdentifier CommitmentTypeIdentifier,
      qualifier   ANY DEFINED BY commitmentTypeIdentifier }

id-cti-ets-proofOfOrigin OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 1}

id-cti-ets-proofOfReceipt OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 2}

id-cti-ets-proofOfDelivery OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 3}

id-cti-ets-proofOfSender OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 4}

id-cti-ets-proofOfApproval OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 5}

id-cti-ets-proofOfCreation OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 6}


-- Signer Location

id-aa-ets-signerLocation OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 17}











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   SignerLocation ::= SEQUENCE { 
       -- at least one of the following shall be present
       countryName    [0]   DirectoryString OPTIONAL, 
          -- As used to name a Country in X.500 
       localityName   [1]   DirectoryString OPTIONAL, 
           -- As used to name a locality in X.500 
       postalAdddress [2]   PostalAddress OPTIONAL }

   PostalAddress ::= SEQUENCE SIZE(1..6) OF DirectoryString

-- Signer Attributes

id-aa-ets-signerAttr OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 18}

   SignerAttribute ::= SEQUENCE OF CHOICE {
      claimedAttributes   [0] ClaimedAttributes,
      certifiedAttributes [1] CertifiedAttributes }

   ClaimedAttributes ::= SEQUENCE OF Attribute 

   CertifiedAttributes ::= AttributeCertificate  
   -- as defined in RFC 3281 : see clause 4.1

-- Content Timestamp

id-aa-ets-contentTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 20}

   ContentTimestamp::= TimeStampToken

-- Signature Timestamp

id-aa-signatureTimeStampToken OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 14}

SignatureTimeStampToken ::= TimeStampToken

-- Complete Certificate Refs.

id-aa-ets-certificateRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 21}

CompleteCertificateRefs ::=  SEQUENCE OF OtherCertID









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-- Complete Revocation Refs

id-aa-ets-revocationRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 22}

   CompleteRevocationRefs ::=  SEQUENCE OF CrlOcspRef

   CrlOcspRef ::= SEQUENCE {
      crlids          [0] CRLListID   OPTIONAL,
      ocspids         [1] OcspListID  OPTIONAL,
      otherRev        [2] OtherRevRefs OPTIONAL
   }

   CRLListID ::=  SEQUENCE {
      crls        SEQUENCE OF CrlValidatedID}

   CrlValidatedID ::=  SEQUENCE {
      crlHash                   OtherHash, 
      crlIdentifier             CrlIdentifier OPTIONAL}

   CrlIdentifier ::= SEQUENCE {
      crlissuer                 Name,
      crlIssuedTime             UTCTime,
      crlNumber                 INTEGER OPTIONAL
}

   OcspListID ::=  SEQUENCE {
       ocspResponses        SEQUENCE OF OcspResponsesID}

   OcspResponsesID ::=  SEQUENCE {
       ocspIdentifier              OcspIdentifier,
       ocspRepHash                 OtherHash    OPTIONAL
   }

   OcspIdentifier ::= SEQUENCE {
      ocspResponderID      ResponderID,    -- As in OCSP response data
      producedAt           GeneralizedTime -- As in OCSP response data
   }

   OtherRevRefs ::= SEQUENCE {
       otherRevRefType   OtherRevRefType,
       otherRevRefs      ANY DEFINED BY otherRevRefType
    }

   OtherRevRefType ::= OBJECT IDENTIFIER








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-- Certificate Values

id-aa-ets-certValues OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 23}

   CertificateValues ::=  SEQUENCE OF Certificate

-- Certificate Revocation Values

id-aa-ets-revocationValues OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 24}

   RevocationValues ::=  SEQUENCE {
      crlVals           [0] SEQUENCE OF CertificateList OPTIONAL,
      ocspVals          [1] SEQUENCE OF BasicOCSPResponse OPTIONAL,
      otherRevVals      [2] OtherRevVals OPTIONAL}

   OtherRevVals ::= SEQUENCE {
       otherRevValType   OtherRevValType,
       otherRevVals      ANY DEFINED BY otherRevValType
   }

   OtherRevValType ::= OBJECT IDENTIFIER


-- CAdES-C Timestamp

id-aa-ets-escTimeStamp OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 25}

ESCTimeStampToken ::= TimeStampToken

-- Time-Stamped Certificates and CRLs

id-aa-ets-certCRLTimestamp OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 26}

TimestampedCertsCRLs ::= TimeStampToken


-- Archive Timestamp

id-aa-ets-archiveTimestamp OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 27}






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ArchiveTimeStampToken ::= TimeStampToken

-- Attribute certificate references

id-aa-ets-attrCertificateRefs OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 44}

AttributeCertificateRefs ::=  SEQUENCE OF OtherCertID

-- Attribute revocation references 

id-aa-ets-attrRevocationRefs OBJECT IDENTIFIER ::= { iso(1) 
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
smime(16) id-aa(2) 45}

AttributeRevocationRefs ::=  SEQUENCE OF CrlOcspRef

END


































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A.2 Signature format definitions using X.680 ASN.1 syntax

NOTE: The ASN.1 module defined in clause A.2 has precedence over that 
       defined in clause A.2 using syntax defined in ITU-T 
       Recommendation X.680 (1997) [8] in the case of any conflict.

ETS-ElectronicSignatureFormats-ExplicitSyntax97 { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-mod(0) 
eSignature-explicit97(29)}

DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS All -

IMPORTS 

-- Cryptographic Message Syntax (CMS): RFC 3852

   ContentInfo, ContentType, id-data, id-signedData, SignedData,
   EncapsulatedContentInfo, SignerInfo,
   id-contentType, id-messageDigest, MessageDigest, id-signingTime, 
   SigningTime, id-countersignature, Countersignature
      FROM CryptographicMessageSyntax2004
      { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
       smime(16) modules(0) cms-2004(24) }

-- ESS Defined attributes: RFC 2634 
-- (Enhanced Security Services for S/MIME)

   id-aa-signingCertificate, SigningCertificate, IssuerSerial,
   id-aa-contentReference, ContentReference, id-aa-contentIdentifier, 
   ContentIdentifier
      FROM ExtendedSecurityServices
      { iso(1) member-body(2) us(840) rsadsi(113549)
       pkcs(1) pkcs-9(9) smime(16) modules(0) ess(2) }

-- Internet X.509 Public Key Infrastructure 
-- Certificate and CRL Profile: RFC 3280 

   Certificate, AlgorithmIdentifier, CertificateList, Name, 
   DirectoryString, Attribute, 
      FROM PKIX1Explicit88 
      {iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0) 
       id-pkix1-explicit(18)}

   GeneralNames, GeneralName, PolicyInformation
      FROM PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) 
      internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) 
      id-pkix1-implicit(19)}


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-- Internet Attribute Certificate Profile for Authorization - RFC 3281

   AttributeCertificate
      FROM PKIXAttributeCertificate {iso(1) identified-organization(3) 
      dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
      id-mod-attribute-cert(12)}

-- OCSP RFC 2560

   BasicOCSPResponse, ResponderID
      FROM OCSP {iso(1) identified-organization(3) dod(6) internet(1)
      security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-ocsp(14)}

-- RFC 3161 Internet X.509 Public Key Infrastructure 
-- Time-Stamp Protocol (TSP)

   TimeStampToken
      FROM PKIXTSP {iso(1) identified-organization(3) dod(6) internet(1)
      security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-tsp(13)} 

   maxSize
      FROM ETS-ElectronicSignaturePolicies-97Syntax { iso(1) 
      member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 
      smime(16) id-mod(0) 8}

;

-- S/MIME Object Identifier arcs used in the present document 
-- ==========================================================

-- S/MIME  OID arc used in the present document
-- id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
-- us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 16 }

-- S/MIME Arcs
-- id-mod  OBJECT IDENTIFIER ::= { id-smime 0 }
-- modules
-- id-ct   OBJECT IDENTIFIER ::= { id-smime 1 }
-- content types
-- id-aa   OBJECT IDENTIFIER ::= { id-smime 2 }
-- attributes
-- id-spq  OBJECT IDENTIFIER ::= { id-smime 5 }
-- signature policy qualifier
-- id-cti  OBJECT IDENTIFIER ::= { id-smime 6 }
-- commitment type identifier

-- Definitions of Object Identifier arcs used in the present document
-- ==================================================================

-- The allocation of OIDs to specific objects are given below 
-- with the associated ASN.1 syntax definition



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-- OID used referencing electronic signature mechanisms based 
-- on the present document for use with the IDUP API (see annex D)

id-etsi-es-IDUP-Mechanism-v1 OBJECT IDENTIFIER ::=
{ itu-t(0) identified-organization(4) etsi(0) 
electronic-signature-standard (1733) part1 (1) idupMechanism (4) 
etsiESv1(1) }

-- Basic ES Attributes Defined in the present document
-- ===================================================

-- CMS Attributes Defined in the present document

-- Mandatory RFC 3852 Electronic Signature Attributes

-- OtherSigningCertificate

id-aa-ets-otherSigCert OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 19 }

   OtherSigningCertificate ::=  SEQUENCE {
      certs        SEQUENCE OF OtherCertID,
      policies     SEQUENCE OF PolicyInformation OPTIONAL
                   -- NOT USED IN THE PRESENT DOCUMENT
   }

   OtherCertID ::= SEQUENCE {
      otherCertHash            OtherHash,
      issuerSerial             IssuerSerial OPTIONAL }

   OtherHash ::= CHOICE {
      sha1Hash OtherHashValue,      -- This contains a SHA-1 hash
      otherHash OtherHashAlgAndValue}

   OtherHashValue ::= OCTET STRING

   OtherHashAlgAndValue ::= SEQUENCE {
      hashAlgorithm   AlgorithmIdentifier,
      hashValue       OtherHashValue }

-- Policy ES Attributes Defined in the present document
-- ====================================================

-- Mandatory Basic Electronic Signature Attributes, plus in addition.
-- Signature Policy Identifier

id-aa-ets-sigPolicyId OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) id-aa(2) 15 }




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   SignaturePolicy ::= CHOICE {
      signaturePolicyId          SignaturePolicyId,
      signaturePolicyImplied     SignaturePolicyImplied 
                              -- not used in this version
   }

   SignaturePolicyId ::= SEQUENCE {
      sigPolicyId           SigPolicyId,
      sigPolicyHash         SigPolicyHash OPTIONAL,
      sigPolicyQualifiers   SEQUENCE SIZE (1..MAX) OF
                                 SigPolicyQualifierInfo OPTIONAL
   }

   SignaturePolicyImplied ::= NULL

   SigPolicyId ::= OBJECT IDENTIFIER

   SigPolicyHash ::= OtherHashAlgAndValue

   SigPolicyQualifierInfo ::= SEQUENCE {
      sigPolicyQualifierId       SIG-POLICY-QUALIFIER.&id
      ({SupportedSigPolicyQualifiers}),
      qualifier               SIG-POLICY-QUALIFIER.&Qualifier
                                ({SupportedSigPolicyQualifiers}
                                    {@sigPolicyQualifierId})OPTIONAL }

   SupportedSigPolicyQualifiers SIG-POLICY-QUALIFIER ::= 
       { noticeToUser | pointerToSigPolSpec }

   SIG-POLICY-QUALIFIER ::= CLASS {
      &id             OBJECT IDENTIFIER UNIQUE,
      &Qualifier      OPTIONAL }
   WITH SYNTAX {
      SIG-POLICY-QUALIFIER-ID     &id
      [SIG-QUALIFIER-TYPE &Qualifier] }

   noticeToUser SIG-POLICY-QUALIFIER ::= {
      SIG-POLICY-QUALIFIER-ID id-spq-ets-unotice SIG-QUALIFIER-TYPE 
      SPUserNotice }

   pointerToSigPolSpec SIG-POLICY-QUALIFIER ::= {
      SIG-POLICY-QUALIFIER-ID id-spq-ets-uri SIG-QUALIFIER-TYPE SPuri }


   id-spq-ets-uri OBJECT IDENTIFIER ::= { iso(1)
    member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
    smime(16) id-spq(5) 1 }

   SPuri ::= IA5String





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   id-spq-ets-unotice OBJECT IDENTIFIER ::= { iso(1)
   member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
   smime(16) id-spq(5) 2 }

   SPUserNotice ::= SEQUENCE {
        noticeRef        NoticeReference OPTIONAL,
        explicitText     DisplayText OPTIONAL}

   NoticeReference ::= SEQUENCE {
        organization     DisplayText,
        noticeNumbers    SEQUENCE OF INTEGER }

   DisplayText ::= CHOICE {
        visibleString    VisibleString  (SIZE (1..200)),
        bmpString        BMPString      (SIZE (1..200)),
        utf8String       UTF8String     (SIZE (1..200)) }

-- Optional Electronic Signature Attributes

-- Commitment Type

id-aa-ets-commitmentType OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 16}

   CommitmentTypeIndication ::= SEQUENCE {
      commitmentTypeId CommitmentTypeIdentifier,
      commitmentTypeQualifier SEQUENCE SIZE (1..MAX) OF
         CommitmentTypeQualifier OPTIONAL}

   CommitmentTypeIdentifier ::= OBJECT IDENTIFIER

   CommitmentTypeQualifier ::= SEQUENCE {
      commitmentQualifierId   COMMITMENT-QUALIFIER.&id,
      qualifier               COMMITMENT-QUALIFIER.&Qualifier OPTIONAL }

   COMMITMENT-QUALIFIER ::= CLASS {
      &id             OBJECT IDENTIFIER UNIQUE,
      &Qualifier      OPTIONAL }
   WITH SYNTAX {
      COMMITMENT-QUALIFIER-ID     &id
      [COMMITMENT-TYPE &Qualifier] }

id-cti-ets-proofOfOrigin OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 1}

id-cti-ets-proofOfReceipt OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 2}

id-cti-ets-proofOfDelivery OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 3}




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id-cti-ets-proofOfSender OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 4}

id-cti-ets-proofOfApproval OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 5}

id-cti-ets-proofOfCreation OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) cti(6) 6}

-- Signer Location

id-aa-ets-signerLocation OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 17}

   SignerLocation ::= SEQUENCE { 
   -- at least one of the following shall be present
      countryName [0] DirectoryString{maxSize} OPTIONAL, 
         -- As used to name a Country in X.500 
      localityName [1] DirectoryString{maxSize} OPTIONAL, 
         -- As used to name a locality in X.500 
      postalAdddress [2] PostalAddress OPTIONAL }

   PostalAddress ::= SEQUENCE SIZE(1..6) OF DirectoryString{maxSize}

-- Signer Attributes

id-aa-ets-signerAttr OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 18}

   SignerAttribute ::= SEQUENCE OF CHOICE {
      claimedAttributes   [0] ClaimedAttributes,
      certifiedAttributes [1] CertifiedAttributes }

   ClaimedAttributes ::= SEQUENCE OF Attribute 

   CertifiedAttributes ::= AttributeCertificate  
   -- as defined in RFC 3281 : see clause 4.1

-- Content Timestamp

id-aa-ets-contentTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 20}

   ContentTimestamp::= TimeStampToken

-- Signature Timestamp

id-aa-signatureTimeStampToken OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 14}

   SignatureTimeStampToken ::= TimeStampToken



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-- Complete Certificate Refs.

id-aa-ets-certificateRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 21}

CompleteCertificateRefs ::=  SEQUENCE OF OtherCertID

-- Complete Revocation Refs

id-aa-ets-revocationRefs OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 22}

   CompleteRevocationRefs ::=  SEQUENCE OF CrlOcspRef

   CrlOcspRef ::= SEQUENCE {
      crlids          [0] CRLListID   OPTIONAL,
      ocspids         [1] OcspListID  OPTIONAL,
      otherRev        [2] OtherRevRefs OPTIONAL
   }

   CRLListID ::=  SEQUENCE {
      crls        SEQUENCE OF CrlValidatedID}

   CrlValidatedID ::=  SEQUENCE {
      crlHash                   OtherHash, 
      crlIdentifier             CrlIdentifier OPTIONAL}

   CrlIdentifier ::= SEQUENCE {
       crlissuer                 Name,
       crlIssuedTime             UTCTime,
       crlNumber                 INTEGER OPTIONAL
   }

   OcspListID ::=  SEQUENCE {
       ocspResponses        SEQUENCE OF OcspResponsesID}

   OcspResponsesID ::=  SEQUENCE {
       ocspIdentifier              OcspIdentifier,
       ocspRepHash                 OtherHash    OPTIONAL
   }

   OcspIdentifier ::= SEQUENCE {
      ocspResponderID      ResponderID,    -- As in OCSP response data
      producedAt           GeneralizedTime -- As in OCSP response data
   }

   OtherRevRefs ::= SEQUENCE {
      otherRevRefType   OTHER-REVOCATION-REF.&id,
      otherRevRefs      SEQUENCE OF OTHER-REVOCATION-REF.&Type
   }




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   OTHER-REVOCATION-REF ::= CLASS {
      &Type, 
      &id   OBJECT IDENTIFIER UNIQUE }
   WITH SYNTAX { 
      WITH SYNTAX &Type ID &id }

-- Certificate Values

id-aa-ets-certValues OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 23}

CertificateValues ::=  SEQUENCE OF Certificate

-- Certificate Revocation Values

id-aa-ets-revocationValues OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 24}

   RevocationValues ::=  SEQUENCE {
     crlVals           [0] SEQUENCE OF CertificateList OPTIONAL,
     ocspVals          [1] SEQUENCE OF BasicOCSPResponse OPTIONAL,
     otherRevVals      [2] OtherRevVals OPTIONAL}

   OtherRevVals ::= SEQUENCE {
      otherRevValType   OTHER-REVOCATION-VAL.&id,
      otherRevVals      SEQUENCE OF OTHER-REVOCATION-REF.&Type
 }

  OTHER-REVOCATION-VAL ::= CLASS {
      &Type, 
      &id   OBJECT IDENTIFIER UNIQUE }
   WITH SYNTAX { 
      WITH SYNTAX &Type ID &id }

-- CAdES-C Timestamp

id-aa-ets-escTimeStamp OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 25}

   ESCTimeStampToken ::= TimeStampToken

-- Time-Stamped Certificates and CRLs

id-aa-ets-certCRLTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 26}

   TimestampedCertsCRLs ::= TimeStampToken

-- Archive Timestamp

id-aa-ets-archiveTimestamp OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 27}

   ArchiveTimeStampToken ::= TimeStampToken

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-- Attribute certificate references

id-aa-ets-attrCertificateRefs OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 44}

   AttributeCertificateRefs ::=  SEQUENCE OF OtherCertID

-- Attribute revocation references 

id-aa-ets-attrRevocationRefs OBJECT IDENTIFIER ::= { iso(1) member-
body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) id-aa(2) 45}

   AttributeRevocationRefs ::=  SEQUENCE OF CrlOcspRef



END





































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Annex B (informative): Extended forms of Electronic Signatures

Clause 4 provides on overview of the various formats of electronic 
signatures included in the present document.  This annex lists the 
attributes that need to be present in the various extended electronic 
signature formats and provide example validation sequences using the 
extended formats.

B.1 Extended forms of validation data

The complete validation data (CAdES-C) described in clause 4.3 and 
illustrated in figure 3 may be extended to create Electronic Signatures 
with extended validation data.  Some Electronic Signatures forms that 
include extended validation are explained below.

An X-Long electronic signature (CAdES-X Long) is when the values of the 
certificates and revocation information are added to the CAdES-C.

This form of Electronic Signature can be useful when the verifier does 
not have direct access to the following information:

   - the signer's certificate;

   - all the CA certificates that make up the full certification path;

   - all the associated revocation status information, as referenced 
     in the CAdES-C.

In some situations additional time-stamps may be created and added to 
the Electronic Signatures as additional attributes.  For example:

   - time-stamping all the validation data as held with the ES (CAdES-
     C), this eXtended validation data is called a CAdES-X Type 1; or

   - time-stamping individual reference data as used for complete 
     validation.  This form of eXtended validation data is called an 
     CAdES-X Type 2.

 NOTE 1: The advantages/drawbacks for CAdES-X Type 1 and CAdES-X Type 2
         are discussed in clause C.4.4.

The above time-stamp forms can be useful when it is required to counter 
the risk that any CA keys used in the certificate chain may be 
compromised.

A combination of the two formats above may be used.  This form of 
eXtended validation data is called an ES X-Long Type 1 or CAdES-X Long 
Type 2.  This form of Electronic Signature can be useful when the 
verifier needs both the values and proof of when the validation data 
existed.




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 NOTE 2: The advantages/drawbacks for CAdES-X long Type 1 and CAdES-X 
         long Type 2 are discussed in clause C.4.6.

B.1.1 CAdES-X Long

An Electronic Signature with the additional validation data forming the 
CAdES-X Long form (CAdES-X-Long)) is illustrated in figure B.1 and 
comprises the following:

   - CAdES-BES or CAdES-EPES as defined in clauses 4.3 , 5.7 or 5.8;

   - complete-certificate-references attribute as defined in clause 
     6.2.1;

   - complete-revocation-references attribute as defined in clause 
     6.2.2.

The following attributes are required if a TSP is not providing a time-
mark of the ES:

   - signature-time-stamp attribute as defined in clause 6.1.1.

The following attributes are required if the full certificate values 
and revocation values are not already included in the CAdES-BES or 
CAdES-EPES:

   - certificate-values attribute as defined in clause 6.3.3;
   - revocation-values attribute, as defined in clause 6.3.4.

If attributes certificates are used then the following attributes may 
be present:

   - attribute-certificate-references attribute defined in clause 
     6.2.3;

   - attribute-revocation-references attribute as defined in clause 
     6.2.4.

Other unsigned attributes may be present, but are not required.

 NOTE: Attribute certificate and revocation references are only 
       present if a user attribute certificate is present in the 
       electronic signature, see clauses 6.2.2 and 6.2.3.











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+---------------------- CAdES-X-Long --------------------------------+
|+-------------------------------------- CAdES-C ---+                |
||                                     +----------+ | +-------------+|
||+----- CAdES-BES or CAdES-EPES ----+ |Timestamp | | |             ||
|||                                  | |over      | | | Complete    ||
|||+---------++----------++---------+| |digital   | | | certificate ||
||||         ||          ||         || |signature | | |    and      ||
||||Signer's ||  Signed  ||Digital  || |          | | | revocation  ||
||||Document ||Attributes||signature|| |Optional  | | |    data     ||
||||         ||          ||         || |when      | | |             ||
|||+---------++----------++---------+| |timemarked| | |             ||
||+----------------------------------+ +----------+ | |             ||
||                                     +-----------+| +-------------+|
||                                     |Complete   ||                |
||                                     |certificate||                |
||                                     |and        ||                |
||                                     |revocation ||                |
||                                     |references ||                |
||                                     +-----------+|                |
|+--------------------------------------------------+                |
|                                                                    |
+--------------------------------------------------------------------+

             Figure B.1 : Illustration of CAdES-X-Long


B.1.2 CAdES-X Type 1

An Electronic Signature with the additional validation data forming the 
eXtended Validation Data - Type 1 X is illustrated in figure B.2 and 
comprises the following:

   - the CAdES-BES or CAdES-EPES as defined in clauses 4.2, 5.7 or 
     5.8;

   - complete-certificate-references attribute as defined in clause 
     6.2.1;

   - complete-revocation-references attribute as defined in clause 
     6.2.2;

   - CAdES-C-Timestamp attribute, as defined in clause 6.3.5.

The following attributes are required if a TSP is not providing a time-
mark of the ES:

   - signature-time-stamp attribute as defined in clause 6.1.1.






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If attributes certificates are used then the following attributes may 
be present:

   - attribute-certificate-references attribute defined in clause 
     6.2.3;

   - attribute-revocation-references attribute as defined in clause 
     6.2.4.

Other unsigned attributes may be present, but are not required.


+------------------------ CAdES-X-Type 1 ----------------------------+
|+---------------------------------- CAdES-C ------+                 |
||                                    +----------+ | +-------------+ |
||+--- CAdES-BES or CAdES-EPES ------+|Timestamp | | |             | |
|||                                  ||over      | | |             | |
|||+---------++----------++---------+||digital   | | |             | |
||||Signer's ||  Signed  || Digital |||signature | | | Timestamp   | |
||||Document ||Attributes||signature|||          | | |    over     | |
||||         ||          ||         |||Optional  | | |   CAdES-C   | |
|||+---------++----------++---------+||when      | | |             | |
||+----------------------------------+|timemarked| | |             | |
||                                    +----------+ | |             | |
||                                    +-----------+| +-------------+ |
||                                    |Complete   ||                 |
||                                    |certificate||                 |
||                                    |   and     ||                 |
||                                    |revocation ||                 |
||                                    |references ||                 |
||                                    +-----------+|                 |
|+-------------------------------------------------+                 |
|                                                                    |
+--------------------------------------------------------------------+

               Figure B.2 : Illustration of CAdES-X Type 1


B.1.3 CAdES-X Type 2

An Electronic Signature with the additional validation data forming the 
eXtended Validation Data - Type 2 X is illustrated in figure B.3.  and 
comprises the following:

   - CAdES-BES or CAdES-EPES as defined in clauses 4.2, 5.7 or 5.8;

   - complete-certificate-references attribute as defined in clause 
     6.2.1;

   - complete-revocation-references attribute as defined in clause 
     6.2.2;


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   - time-stamped-certs-crls-references attribute as defined in clause 
     6.3.6.

The following attributes are required if a TSP is not providing a time-
mark of the ES:

   - signature-time-stamp attribute as defined in clause 6.1.1.

If attributes certificates are used then the following attributes may 
be present:

   - attribute-certificate-references attribute defined in clause 
     6.2.3;

   - attribute-revocation-references attribute as defined in clause 
     6.2.4.

Other unsigned attributes may be present, but are not required.



+----------------------- CAdES-X-Type 2 -----------------------------+
|+-------------------------------------- CAdES-C --+                 |
||                                    +----------+ |                 |
||+-- CAdES-BES or CAdES-EPES -------+|Timestamp | |                 |
|||                                  ||over      | |                 |
|||+---------++----------++---------+||digital   | | +-------------+ |
||||         ||          ||         |||Signature | | | Timestamp   | |
||||Signer's ||  Signed  || Digital |||          | | | only over   | |
||||Document ||Attributes||signature|||Optional  | | | Complete    | |
||||         ||          ||         |||when      | | | certificate | |
|||+---------++----------++---------+||Timemarked| | |    and      | |
||+----------------------------------++----------+ | | revocation  | |
||                                    +-----------+| | references  | |
||                                    |Complete   || +-------------+ |
||                                    |certificate||                 |
||                                    |and        ||                 |
||                                    |revocation ||                 |
||                                    |references ||                 |
||                                    +-----------+|                 |
|+-------------------------------------------------+                 |
|                                                                    |
+--------------------------------------------------------------------+

               Figure B.3 : Illustration of CAdES-X Type 2



B.1.4 CAdES-X Long Type 1 and CAdES-X Long Type 2

An Electronic Signature with the additional validation data forming the 
CAdES-X Long Type 1 and CAdES-X Long Type 2 is illustrated in 
figure B.4 and comprises the following:

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   - CAdES-BES or CAdES-EPES as defined in clauses 4.3, 5.7 or 5.8;

   - complete-certificate-references attribute as defined in clause 
     6.2.1;

   - complete-revocation-references attribute as defined in clause 
     6.2.2;

The following attributes are required if a TSP is not providing a time-
mark of the ES:

   - signature-time-stamp attribute as defined in clause 6.1.1.

The following attributes are required if the full certificate values 
and revocation values are not already included in the CAdES-BES or 
CAdES-EPES:
   - certificate-values attribute as defined in clause 6.3.3;
   - revocation-values attribute, as defined in clause 6.3.4.

If attributes certificates are used then the following attributes may 
be present:

   - attribute-certificate-references attribute defined in clause 
     6.2.3;

   - attribute-revocation-references attribute as defined in clause 
     6.2.4.

Plus one of the following attributes is required:

   - CAdES-C-Timestamp attribute, as defined in clause 6.3.5;
   - time-stamped-certs-crls-references attribute as defined in clause 
     6.3.6.

Other unsigned attributes may be present, but are not required.



















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 +---------------------- CAdES-X-Type 1 or 2 ------------------------+
 |                                                   +--------------+|
 |+-------------------------------------- CAdES-C --+|+------------+||
 ||                                    +----------+ ||| Timestamp  |||
 ||+-- CAdES-BES or CAdES-EPES -------+|Timestamp | |||    over    |||
 |||                                  ||over      | |||  CAdES-C   |||
 |||+---------++----------++---------+||digital   | | +------------+ |
 ||||         ||          ||         |||signature | ||      or      ||
 ||||Signer's ||  Signed  || Digital |||          | ||+------------+||
 ||||Document ||Attributes||Signature|||Optional  | ||| Timestamp  |||
 ||||         ||          ||         |||when      | ||| only over  |||
 |||+---------++----------++---------+||timemarked| ||| complete   |||
 ||+----------------------------------++----------+ ||| certificate|||
 ||                                                 |||    and     |||
 ||                                    +-----------+||| revocation |||
 ||                                    |Complete   |||| references |||
 ||                                    |certificate|||+------------+||
 ||                                    |and        ||+--------------+|
 ||                                    |revocation || +------------+ |
 ||                                    |references || |Complete    | |
 ||                                    +-----------+| |certificate | |
 |+-------------------------------------------------+ |   and      | |
 |                                                    |revocation  | |
 |                                                    |  values    | |
 |                                                    +------------+ |
 +-------------------------------------------------------------------+

           Figure B.4 : Illustration of CAdES-X Long Type 1
                        and CAdES-X Long Type 2


B.2 Timestamp extensions

Each instance of time-stamp attribute may include as unsigned 
attributes in the signedData of the timestamp the following attribute 
related to the TSU:

   - complete-certificate-references attribute of the TSU as defined 
     in clause 6.2.1;

   - complete-revocation-references attribute of the TSU as defined in 
     clause 6.2.2;

   - certificate-values attribute; of the TSU as defined in clause 
     6.3.3;

   - revocation-values attribute, of the TSU as defined in clause 
     6.3.4.

Other unsigned attributes may be present, but are not required.



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B.3 Archive validation data (CAdES-A)

Before the algorithms, keys and other cryptographic data used at the 
time the CAdES-C was built become weak and the cryptographic functions 
become vulnerable, or the certificates supporting previous time-stamps 
expires, the signed data, the CAdES-C and any additional information 
(i.e. any CAdES-X) should be time-stamped.  If possible this should use 
stronger algorithms (or longer key lengths) than in the original time-
stamp.  This additional data and time-stamp is called Archive 
Validation Data required for the ES Archive format (CAdES-A).  The 
Time-stamping process may be repeated every time the protection used to 
time-stamp a previous CAdES-A becomes weak.  An CAdES-A may thus bear 
multiple embedded time stamps.

An example of an Electronic Signature (ES), with the additional 
validation data for the CAdES-C and CAdES-X forming the CAdES-A is 
illustrated in figure B.5.


+--------------------------- CAdES-A---------------------------------+
|+----------------------------------------------------+              |
||                                    +--------------+| +----------+ |
||+--------------------- CAdES-C ----+|+------------+|| |          | |
|||                     +----------+ ||| Timestamp  ||| |          | |
|||+-- CAdES-BES ------+|Timestamp | |||   over     ||| |          | |
||||   or CAdES-EPES   ||over      | |||  CAdES-C   ||| |  Archive | |
||||                   ||digital   | ||+------------+|| |          | |
||||                   ||signature | ||     or       || |Timestamp | |
||||                   ||          | ||+------------+|| |          | |
||||                   ||optional  | ||| Timestamp  ||| |          | |
||||                   ||when      | ||| only over  ||| |          | |
||||                   ||timemarked| ||| complete   ||| |          | |
|||+-------------------++----------+ ||| certificate||| +----------+ |
|||                                  |||    and     |||              |
|||                   +-------------+||| revocation |||              |
|||                   | Complete    |||| references |||              |
|||                   | certificate |||+------------+||              |
|||                   | and         ||+--------------+|              |
|||                   | revocation  || +------------+ |              |
|||                   | references  || |Complete    | |              |
|||                   +-------------+| |certificate | |              |
||+----------------------------------+ |   and      | |              |
||                                     |revocation  | |              |
||                                     |  values    | |              |
||                                     +------------+ |              |
|+----------------------------------------------------+              |
+--------------------------------------------------------------------+

                    Figure B.5 : Illustration of CAdES-A





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The CAdES-A comprises the following elements:

   - the CAdES-BES or CAdES-EPES including their signed and unsigned 
     attributes;

   - complete-certificate-references attribute as defined in clause 
     6.2.1;

   - complete-revocation-references attribute as defined in clause 
     6.2.2.

The following attributes are required if a TSP is not providing a time-
mark of the ES:

   - signature-time-stamp attribute as defined in clause 6.1.1.

If attributes certificates are used then the following attributes may 
be present:

   - attribute-certificate-references attribute defined in clause 
     6.2.3;
   - attribute-revocation-references attribute as defined in clause 
     6.2.4.

The following attributes are required if the full certificate values 
and revocation values are not already included in the CAdES-BES or 
CAdES-EPES:

   - certificate-values attribute as defined in clause 6.3.3;
   - revocation-values attribute as defined in clause 6.3.4.

At least one of the following two attributes is required:

   - CAdES-C-Timestamp attribute as defined in clause 6.3.5;

   - time-stamped-certs-crls-references attribute as defined in clause 
     6.3.6.

The following attribute is required:

   - archive-time-stamp attributes defined in clause 6.4.1.

Several instances of archive-time-stamp attribute may occur with an 
electronic signature both over time and from different TSUs.  The time-
stamp should be created using stronger algorithms (or longer key 
lengths) than in the original electronic signatures or time-stamps.

Other unsigned attributes of the ES may be present, but are not 
required.





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The archive timestamp will itself contain the certificate and 
revocation information required to validate the archive timestamp, this 
may include the following unsigned attributes:

   - complete-certificate-references attribute of the TSU as defined 
     in clause 6.2.1;

   - complete-revocation-references attribute of the TSU as defined in 
     clause 6.2.2;

   - certificate-values attribute of the TSU as defined in clause 
     6.3.3;

   - revocation-values attribute of the TSU as defined in clause 
     6.3.4.

Other unsigned attributes may be present, but are not required.


B.4 Example validation sequence

As described earlier the signer or initial verifier may collect all the 
additional data that forms the electronic signature.  Figure B.6, and 
subsequent description, describes how the validation process may build 
up a complete electronic signature over time.




























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  +------------------------------------------ CAdES-C -------------+
  |+------------------------------- CAdES-T ------+                |
  ||+-------------- CAdES ------------+           |                |
  |||+--------------------++---------+|+---------+|  +-----------+ |
  |||| ________           ||         |||Timestamp||  |Complete   | |
  |||||Sign.Pol|          ||Digital  |||over     ||  |certificate| |
  |||||  Id.   | Signed   ||signature|||digital  ||  |   and     | |
  ||||| option.|attributes||         |||signature||  |revocation | |
  |||||________|          |+---------+|+---------+|  |references | |
  |||+--------------------+           |    ^      |  +-----------+ |
  ||+---------------------------------+    |      |        ^       |
  ||                     1 |              /       |        |       |
  |+---------------------- | ------------/--------+        |       |
  +----------------------- | ---------- / --------------- / -------+
                           |           /2    ----3--------
        +----------+       |          /     /
        |          |       v         /     |
        | Signer's |      +---------------------+     +-------------+
        | document |----->| Validation Process  |---->|- Valid      |
        |          |      +---------------------+ 4   |- Invalid    |
        +----------+           |  ^       |  ^        |- Validation |
                               v  |       v  |        |  Incomplete |
                           +---------+ +--------+     +-------------+
                           |Signature| |Trusted |
                           | Policy  | |Service |
                           | Issuer  | |Provider|
                           +---------+ +--------+

         Figure B.6 : Illustration of a CAdES validation sequence


Soon after receiving the Electronic Signature (CAdES) from the signer 
(1), the digital signature value may be checked; the validation process 
shall at least add a time-stamp (2), unless the signer has provided one 
which is trusted by the verifier.  The validation process may also 
validate the electronic signature, using additional data (e.g. 
certificates, CRL, etc.) provided by trusted service providers.  When 
applicable, the validation process will also need to conform to the 
requirements specified in a signature policy.  If the validation 
process is validation incomplete, then the output from this stage is 
the CAdES-T.

To ascertain the validity status as Valid or Invalid and communicate 
that to the user (4) all the additional data required to validate the 
CAdES-C, must be available (e.g. the complete certificate and 
revocation information).

Once the data needed to complete validation data references (CAdES-C) 
is available then the validation process should:

   - obtain all the necessary additional certificate and revocation 
     status information;


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   - complete all the validation checks on the ES, using the complete 
     certificate and revocation information (if a time-stamp is not 
     already present, this may be added at the same stage combining 
     CAdES-T and CAdES-C process);

   - record the complete certificate and revocation references (3);

   - indicate the validity status to the user (4).

At the same time as the validation process creates the CAdES-C, the 
validation process may provide and/or record the values of certificates 
and revocation status information used in CAdES-C, called the CAdES-X 
Long (5).

This is illustrated in figure B.7.

+----------------------------------------------------- CAdES-X Long -+
|+------------------------------- CAdES-C -------------+             |
||+-------------- CAdES ------------+                  |             |
|||+--------------------++---------+|+---------+       |+-----------+|
|||| ________           ||         |||Timestamp|       ||Complete   ||
|||||Sign.Pol|          ||Digital  |||over     |       ||certificate||
|||||  Id.   | Signed   ||signature|||digital  |       ||   and     ||
||||| option.|attributes||         |||signature|       ||revocation ||
|||||________|          ||         ||+---------+       ||  values   ||
|||+--------------------++---------+|  ^  +-----------+|+-----------+|
||+---------------------------------+  |  |Complete   ||      ^      |
||                         |           |  |certificate||      |      |
||                         |         2 |  |   and     ||      |      |
||                         |           |  |revocation ||      |      |
||                         |           |  |references ||      |      |
||                       1 |          /   +-----------+|      |      |
|+------------------------ | ------- / --------- ^-----+     /       |
+------------------------- | ------ / ---------- |--------- / -------+
                           |       /      ----- /  ------- /
      +----------+         |      /      /  3     /   5
      |          |         v     |      |        |
      | Signer's |      +--------------------+      +-----------+
      | document |----->| Validation Process |----->| - Valid   |
      |          |      +--------------------+  4   | - Invalid |
      +----------+          |  ^       |  ^         +-----------+
                            v  |       v  |
                        +---------+ +--------+
                        |Signature| |Trusted |
                        | Policy  | |Service |
                        | Issuer  | |Provider|
                        +---------+ +--------+

          Figure B.7 : Illustration of a CAdES validation sequence
                       with CAdES-X Long




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When the validation process creates the CAdES-C it may also create 
extended forms of validation data.

A first alternative is to time-stamp all data forming the CAdES-X Type 
1 (6).

This is illustrated in figure B.8.

+------------------------------------------------ CAdES-X Type 1 -----+
|+------------------------------- CAdES-C ------------------+         |
||+-------------- CAdES ------------+                       |         |
|||+--------------------++---------+|+---------++----------+|+-------+|
|||| ________           ||         |||Timestamp|| Complete |||       ||
|||||Sign.Pol|          ||Digital  |||over     ||  cert.   |||Time-  ||
|||||  Id.   | Signed   ||signature|||digital  ||   and    |||stamp  ||
||||| option.|attributes||         |||signature||  revoc.  ||| over  ||
|||||________|          |+---------+|+---------+|references|||CAdES-C||
|||+--------------------+           |    ^      |          |||       ||
||+---------------------------------+    |      +----------+|+-------+|
||                         |             |            ^     |    ^    |
||                       1 |            /             |     |    |    |
|+------------------------ | --------- / ----------- / -----+    |    |
+------------------------- | -------- / ----------- / --------- / ----+
                           |       2 /     ---3----            /
      +----------+         |        /    /   -----------5------
      |          |         v       |    |  /
      | Signer's |      +--------------------+       +-----------+
      | document |----->| Validation Process |-----> | - Valid   |
      |          |      +--------------------+  4    | - Invalid |
      +----------+          |  ^       |  ^          +-----------+
                            v  |       v  |
                        +---------+ +--------+
                        |Signature| |Trusted |
                        | Policy  | |Service |
                        | Issuer  | |Provider|
                        +---------+ +--------+

    Figure B.8  : Illustration of CAdES with eXtended Validation Data
                  CAdES-X Type 1


Another alternative is to time-stamp the certificate and revocation 
information references used to validate the electronic signature (but 
not the signature) (6'); this is called CAdES-X Type 2.

This is illustrated in figure B.9.







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 +-------------------------------------------- CAdES-X Type 2 --------+
 |+------------------------------- CAdES-C -------------+             |
 ||+-------------- CAdES ------------+                  |             |
 |||+--------------------++---------+|+---------+       |+-----------+|
 |||| ________           ||         |||Timestamp|       ||Timestamp  ||
 |||||Sign.Pol|          ||         |||over     |       ||   over    ||
 |||||  Id.   | Signed   ||Digital  |||digital  |       ||complete   ||
 ||||| option.|attributes||signature|||signature|       ||certificate||
 |||||________|          ||         |||         |       ||           ||
 |||+--------------------++---------+|+---------+       ||   and     ||
 ||+---------------------------------+  ^  +-----------+||revocation ||
 ||                         |           |  |Complete   |||references ||
 ||                         |           |  |certificate||+-----------+|
 ||                         |           |  |   and     ||     ^       |
 ||                       1 |         2 |  |revocation ||     |       |
 ||                         |           |  |references ||     |       |
 ||                         |           |  +-----------+|     |       |
 |+------------------------ | --------- | --- ^ --------+     |       |
 |                          |           |   3 |              /        |
 |                          |           |    /    ----------          |
 |                          |          /    /    /   5                |
 |                          |         /    /    /                     |
 |                          |        /    /    /                      |
 +------------------------- | ----- | -- | -- / ----------------------+
                            |       |    |   |
                            v       |    |   |
                         +--------------------+      +-----------+
                         | Validation Process |----->| - Valid   |
                         +--------------------+  4   | - Invalid |
                             |  ^       |  ^         +-----------+
                             v  |       v  |
                         +---------+ +--------+
                         |Signature| |Trusted |
                         | Policy  | |Service |
                         | Issuer  | |Provider|
                         +---------+ +--------+

    Figure B.9: Illustration of CAdES with eXtended Validation Data
                CAdES-X Type 2

Before the algorithms used in any of electronic signatures become or 
are likely, to be compromised or rendered vulnerable in the future, it 
may be necessary to time-stamp the entire electronic signature, 
including all the values of the validation and user data as an ES with 
Archive Validation Data (CAdES-A) (7).







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An CAdES-A is illustrated in figure B.10.

  +----------------------------- CAdES-A ---------------------------+
  |                                                                 |
  |  +-- CAdES-X Long Type 1 or 2  ----------+                      |
  |  |                                       |   +------------+     |
  |  |                                       |   |            |     |
  |  |                                       |   |  Archive   |     |
  |  |                                       |   | Time-stamp |     |
  |  |                                       |   |            |     |
  |  |                                       |   +------------+     |
  |  +---------------------------------------+         ^            |
  |  +----------+          ^   ^   ^   ^               |            |
  |  |          |          |   |   |   |              /             |
  |  | Signers' |          |   |   |   |             /              |
  |  | Document |\         |   |   |   |            /               |
  |  |          | \ 1    2 | 3 | 5 | 6 |         7 /                |
  |  +----------+  \       |   |   |   |          /                 |
  |                 \      |   |   |   |         /                  |
  +----------------- \ --- | - | - | - | ------ / ------------------+
                      \    |   |   |   |       |
                       |   |   |   |   |       |
                       |   |   |   |   |       |
                       v   v   |   |   |       |
                   +-----------------------------+      +-----------+
                   |      Validation Process     |----->| - Valid   |
                   +-----------------------------+  4   | - Invalid |
                       |  ^       |  ^                  +-----------+
                       v  |       v  |
                   +---------+ +--------+
                   |Signature| |Trusted |
                   | Policy  | |Service |
                   | Issuer  | |Provider|
                   +---------+ +--------+

                   Figure B.10: Illustration of CAdES-A

B.5 Additional optional features

The present document also defines additional optional features to:

   - indicate a commitment type being made by the signer;

   - indicate the claimed time when the signature was done;

   - indicate the claimed location of the signer;

   - indicate the claimed or certified role under which a signature 
     was created;

   - support counter signatures;

   - support multiple signatures.


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Annex C (informative):General description

This annex explains some of the concepts and provides the rational for 
normative parts of the present document.

The specification below includes a description why and when the each 
component of an electronic signature is useful, with a brief 
description of the vulnerabilities and threats and the manner by which 
they are countered.

C.1 The signature policy

The signature policy is a set of rules for the creation and validation 
of an electronic signature, under which the signature can be determined 
to be valid.  A given legal/contractual context may recognize a 
particular signature policy as meeting its requirements.  A signature 
policy may be issued, for example, by a party relying on the electronic 
signatures and selected by the signer for use with that relying party.  
Alternatively, a signature policy may be established through an 
electronic trading association for use amongst its members.  Both the 
signer and verifier use the same signature policy.

The signature policy may be explicitly identified or may be implied by 
the semantics of the data being signed and other external data like a 
contract being referenced which itself refers to a signature policy.
An explicit signature policy has a globally unique reference, which is 
bound to an electronic signature by the signer as part of the signature 
calculation.

The signature policy needs to be available in human readable form so 
that it can be assessed to meet the requirements of the legal and 
contractual context in which it is being applied.  To facilitate the 
automatic processing of an electronic signature the parts of the 
signature policy which specifies the electronic rules for the creation 
and validation of the electronic signature also needs to be 
comprehensively defined and in a computer processable form.

The signature policy thus includes the following:

   - rules, which apply to technical validation of a particular 
     signature;

   - rules which may be implied through adoption of Certificate 
     Policies that apply to the electronic signature (e.g. rules for 
     ensuring the secrecy of the private signing key);

   - rules, which relate to the environment used by the signer, e.g. 
     the use of an agreed CAD (Card Accepting Device) used in 
     conjunction with a smart card.





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For example, the major rules required for technical validation can 
include: recognized root keys or "top-level certification authorities", 
acceptable certificate policies (if any), necessary certificate 
extensions and values (if any), the need for the revocation status for 
each component of the certification tree, acceptable TSAs (if time-
stamp tokens are being used), acceptable organizations for keeping the 
audit trails with time-marks (if time-marking is being used), 
acceptable AAs (if any are being used).as well as rules defining the 
components of the electronic signature that shall be provided by the 
signer with data required by the verifier when required to provide long 
term proof.

C.2 Signed information

The information being signed may be defined as a MIME-encapsulated 
message which can be used to signal the format of the content in order 
to select the right display or application.  It can be composed of 
formatted data, free text or fields from an electronic form (e-form).  
For example, the Adobe(tm) format "pdf" may be used or the eXtensible Mark 
up Language (XML).  Annex D defines how the content may be structured 
to indicate the type of signed data using MIME.

C.3 Components of an electronic signature

C.3.1 Reference to the signature policy

When two independent parties want to evaluate an electronic signature, 
it is fundamental that they get the same result.  This requirement can 
be met using comprehensive signature policies that ensure consistency 
of signature validation.  Signature policies can be identified 
implicitly by the data being signed or they can be explicitly 
identified using the CAdES-EPES form of electronic signature, the 
CAdES-EPES mandates a consistent signature policy must be used by both 
the signer and verifier.

By signing over the signature policy identifier in the CAdES-EPES the 
signer explicitly indicates that he or she has applied the signature 
policy in creating the signature.

In order to unambiguously identify the details of an explicit signature 
policy that is to be used to verify a CAdES-EPES the signature an 
identifier and hash of the "Signature policy" shall be part of the 
signed data.  Additional information about the explicit policy (e.g. 
web reference to the document) may be carried as "qualifiers" to the 
signature policy identifier.

In order to unambiguously identify the authority responsible for 
defining an explicit signature policy the "Signature policy" can be 
signed.




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C.3.2 Commitment type indication

The commitment type can be indicated in the electronic signature 
either:

   - explicitly using a "commitment type indication" in the electronic 
     signature;

   - implicitly or explicitly from the semantics of the signed data.

If the indicated commitment type is explicit using a "commitment type 
indication" in the electronic signature, acceptance of a verified 
signature implies acceptance of the semantics of that commitment type.  
The semantics of explicit commitment types indications may be subject 
to signer and verifier agreement, specified as part of the signature 
policy or registered for generic use across multiple policies.

If a CAdES-EPES electronic signature format is used and the electronic 
signature includes a commitment type indication other than one of those 
recognized under the signature policy the signature shall be treated as 
invalid.

How commitment is indicated using the semantics of the data being 
signed is outside the scope of the present document.

 NOTE: Examples of commitment indicated through the semantics of the 
       data being signed, are:

   - an explicit commitment made by the signer indicated by the type 
     of data being signed over.  Thus, the data structure being signed 
     can have an explicit commitment within the context of the 
     application (e.g. EDIFACT purchase order);

   - an implicit commitment which is a commitment made by the signer 
     because the data being signed over has specific semantics 
     (meaning) which is only interpretable by humans, (i.e. free 
     text).

C.3.3 Certificate identifier from the signer

In many real life environments users will be able to get from different 
CAs or even from the same CA, different certificates containing the 
same public key for different names.  The prime advantage is that a 
user can use the same private key for different purposes.  Multiple use 
of the private key is an advantage when a smart card is used to protect 
the private key, since the storage of a smart card is always limited.  
When several CAs are involved, each different certificate may contain a 
different identity, e.g. as a national or as an employee from a 
company.  Thus when a private key is used for various purposes, the 
certificate is needed to clarify the context in which the private key 
was used when generating the signature.  Where there is the possibility 
of multiple use of private keys it is necessary for the signer to 
indicate to the verifier the precise certificate to be used.

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Many current schemes simply add the certificate after the signed data 
and thus are vulnerable to substitution attacks.  If the certificate 
from the signer was simply appended to the signature and thus not 
protected by the signature, any one could substitute one certificate by 
another and the message would appear to be signed by some one else.  In 
order to counter this kind of attack, the identifier of the signer has 
to be protected by the digital signature from the signer.

In order to identify unambiguously the certificate to be used for the 
verification of the signature an identifier of the certificate from the 
signer shall be part of the signed data.

C.3.4 Role attributes

While the name of the signer is important, the position of the signer 
within a company or an organization of paramount importance as well.  
Some information (i.e. a contract) may only be valid if signed by a 
user in a particular role, e.g. a Sales Director.  In many cases who 
the sales Director really is, is not that important but being sure that 
the signer is empowered by his company to be the Sales Director is 
fundamental.

The present document defines two different ways for providing this 
feature:

   - by placing a claimed role name in the CMS signed attributes 
     field;

   - by placing an attribute certificate containing a certified role 
     name in the CMS signed attributes field.

 NOTE: Another possible approach would have been to use additional 
       attributes containing the roles name(s) in the signer's 
       identity certificate However, it was decided not to follow 
       this approach as it significantly complicates the management 
       of certificates.  For example by using separate certificates 
       for signer's identity and roles means new identity keys need 
       not be issued if a user's role changes.

C.3.4.1 Claimed role

The signer may be trusted to state his own role without any certificate 
to corroborate this claim.  In which case the claimed role can be added 
to the signature as a signed attribute.









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C.3.4.2 Certified role

Unlike public key certificates that bind an identifier to a public key, 
Attribute Certificates bind the identifier of a certificate to some 
attributes, like a role.  An Attribute Certificate is NOT issued by a 
CA but by an Attribute Authority (AA).  The Attribute Authority in most 
cases might be under the control of an organization or a company that 
is best placed to know which attributes are relevant for which 
individual.  The Attribute Authority may use or point to public key 
certificates issued by any CA, provided that the appropriate trust may 
be placed in that CA.  Attribute Certificates may have various periods 
of validity.  That period may be quite short, e.g. one day.  While this 
requires that a new Attribute Certificate be obtained every day, valid 
for that day, this can be advantageous since revocation of such 
certificates may not be needed.  When signing, the signer will have to 
specify which Attribute Certificate it selects.  In order to do so, the 
Attribute Certificate will have to be included in the signed data in 
order to be protected by the digital signature from the signer.

In order to identify unambiguously the attribute certificate(s) to be 
used for the verification of the signature an identifier of the 
attribute certificate(s) from the signer shall be part of the signed 
data.

C.3.5 Signer location

In some transactions the purported location of the signer at the time 
he or she applies his signature may need to be indicated.  For this 
reason an optional location indicator shall be able to be included.

In order to provide indication of the location of the signer at the 
time he or she applied his signature a location attribute may be 
included in the signature.
C.3.6 Signing time

The present document provides the capability to include a claimed 
signing time as an attribute of an electronic signature.

Using this attribute a signer may sign over a time which is the claimed 
signing time.  When an ES with Time-stamp is created (CAdES-T) then 
either a trusted time stamp is obtained and added to the ES or a 
trusted time mark exists in an audit trail.  When a verifier accepts a 
signature, the two times shall be within acceptable limits.  In all 
cases, the claimed signing time cannot be after the time identified by 
the time-stamp or time-mark.

A further optional attribute is defined in the present document to 
timestamp the content, to provide proof of the existence of the 
content, at the time indicated by the time-stamp token.





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Using this optional attribute a trusted secure time may be obtained 
before the document is signed and included under the digital signature.  
This solution requires an on-line connection to a trusted time-stamping 
service before generating the signature and may not represent the 
precise signing time, since it can be obtained in advance.  However, 
this optional attribute may be used by the signer to prove that the 
signed object existed before the date included in the time-stamp (see 
clause 5.11.4).

Also, the signing time, if present should be between the time indicated 
by this time-stamp and time indicated by the CAdES-T time-stamp.

C.3.7 Content format

When presenting signed data to a human user it may be important that 
there is no ambiguity as to the presentation of the signed information 
to the relying party.  In order for the appropriate representation 
(text, sound or video) to be selected by the relying party a content 
hint may be indicated by the signer.  If a relying party system does 
not use the format specified in the content hints attribute to present 
the data to the relying party, then a human relying party may 
misinterpret data with valid signatures.

C.3.8 Content cross referencing

When presenting a signed data is in related to another signed data, it 
may be important to identify the signed data to which it relates to.  
The Content-reference and Content-identifier attributes as defined in 
ESS (RFC 2634 [5]) provide the ability to link a request and reply 
messages in an exchange between two parties.

C.4 Components of validation data

C.4.1 Revocation status information

A verifier will have to ascertain that the certificate of the signer 
was valid at the time of the signature.  This can be done by either:

   - using Certificate Revocation Lists (CRLs);

   - using responses from an on-line certificate status server (for 
     example; obtained through the OCSP protocol).

 NOTE 1: The time of the signature may not be know, so time-stamping 
         or time-marking may be used to provide the time indication of 
         when it was known the signature existed.

 NOTE 2: When validating an electronic signature and checking 
         revocation status information a "grace period" is required 
         which needs to be suitably long enough to allow the involved 




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         authority to process a "last minute" revocation request and 
         for the request to propagate through the revocation system.  
         This grace period is to be added to the time included with the 
         timestamp token or the time mark and thus the revocation 
         status information should be captured after the end of the 
         grace period.

C.4.1.1 CRL information

When using CRLs to get revocation information, a verifier will have to 
make sure that he or she gets at the time of the first verification the 
appropriate certificate revocation information from the signer's CA.  
This should be done as soon as possible to minimize the time delay 
between the generation and verification of the signature.  However, a 
"grace period" is required to allow CAs time to process revocation 
requests. 

For example, a revocation request may arrive at a CA just before 
issuing the next CRL and there may not enough time to include the 
revised revocation status information.  This involves checking that the 
signer certificate serial number is not included in the CRL.  The 
signer, the initial or subsequent verifier may obtain either this CRL.  
If obtained by the signer, then it shall be conveyed to the verifier.  
It may be convenient to archive the CRL for ease of subsequent 
verification or arbitration.  Alternatively, provided the CRL is 
archived elsewhere which is accessible for the purpose of arbitration, 
then the serial number of the CRL used may be archived together with 
the verified electronic signature as an CAdES-C form.

Even if the certificate serial number appears in the CRL with the 
status "suspended" (i.e. on hold), the signature is not to be deemed as 
valid since a suspended certificate is not supposed to be used even by 
its rightful owner.

C.4.1.2 OCSP information

When using OCSP to get revocation information, a verifier will have to 
make sure that he or she gets at the time of the first verification an 
OCSP response that contains the status "valid".  This should be done as 
soon as possible after the generation of the signature, still providing 
a "grace period" suitable enough to allow the involved authority to 
process a "last minute" revocation request The signer, the verifier or 
any other third party may fetch this OCSP response.  Since OCSP 
responses are transient and thus are not archived by any TSP including 
CA, it is the responsibility of every verifier to make sure that it is 
stored in a safe place.  The simplest way is to store them associated 
with the electronic signature.  An alternative would be to store them 
in some storage so that they can then be easily retrieved, and 
incorporate references to them in the electronic signature itself as an 
CAdES-C form.




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In the same way as for the case of the CRL, it may happen that the 
certificate is declared as invalid but with the secondary status 
"suspended".  In such a case, same comment as for CRL applies.

C.4.2 Certification path

A verifier may have to ascertain that the certification path was valid, 
at the time of the signature, up to a trust point according to the:

   - naming constraints;
   - certificate policy constraints;
   - Signature Policy, when applicable.

Since the time of the signature cannot be known with certainty, an 
upper limit of it should be used as indicated by either the time stamp 
or time mark.

In this case it will be necessary to capture all the certificates from 
the certification path, starting with those from the signer and ending 
up with those of the self-signed certificate from one trusted root, 
when applicable this may be specified as part of the Signature Policy.  
In addition, it will be necessary to capture the Certificate Authority 
Revocation Lists (CARLs) to prove than none of the CAs from the chain 
was revoked at the time of the signature.  Again, all this material may 
be incorporated in the electronic signature (ES X forms).  An 
alternative would be to store it in some storage so that they can it be 
easily retrieved, and incorporate references to it in the electronic 
signature itself as an CAdES-C form.

C.4.3 Time-stamping for long life of signatures

An important property for long standing signatures is that a signature, 
having been found once to be valid, shall continue to be so months or 
years later.

A signer, verifier or both may be required to provide on request, proof 
that a digital signature was created or verified during the validity 
period of the all the certificates that make up the certificate path.  
In this case, the signer, verifier or both will also be required to 
provide proof that the signer's certificate and all the CA certificates 
used to form a valid certification path were not revoked when the 
signature was created or verified.

It would be quite unacceptable, to consider a signature as invalid even 
if the keys or certificates were later compromised.  Thus there is a 
need to be able to demonstrate that the signature keys was valid at the 
time that the signature was created to provide long term evidence of 
the validity of a signature.

It could be the case that a certificate was valid at the time of the 
signature but revoked some time later.  In this event, evidence shall 



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be provided that the document was signed before the signing key was 
revoked.  Time-stamping by a Time-Stamping Authority (TSA) can provide 
such evidence.  A time stamp is obtained by sending the hash value of 
the given data to the TSA.  The returned "time-stamp" is a signed 
document that contains the hash value, the identity of the TSA, and the 
time of stamping.  This proves that the given data existed before the 
time of stamping.  Time-stamping a digital signature (by sending a hash 
of the signature to the TSA) before the revocation of the signer's 
private key, provides evidence that the signature has been created 
before the key was revoked.

If a recipient wants to hold a valid electronic signature he will have 
to ensure that he has obtained a valid time stamp for it, before that 
key (and any key involved in the validation) is revoked.  The sooner 
the time-stamp is obtained after the signing time, the better.  Any 
time stamp or time mark that is taken after the expiration date of any 
certificate in the certification path has no value in proving the 
validity of a signature.

It is important to note that signatures may be generated "off-line" and 
time-stamped at a later time by anyone, for example by the signer or 
any recipient interested in the value of the signature.  The time stamp 
can thus be provided by the signer together with the signed document, 
or obtained by the recipient following receipt of the signed document.

The time stamp is NOT a component of the Basic Electronic Signature, 
but the essential component of the ES with Time-stamp.

It is required in the present document that if a signer's digital 
signature value is to be time-stamped, the Time-Stamp Token is issued 
by a trusted source, known as a Time-stamping Authority.

The present document requires that the signer's digital signature value 
is time-stamped by a trusted source before the electronic signature can 
become an ES with Complete validation data.  Acceptable TSAs may be 
specified in a Signature Validation Policy.

This technique is referred to as CAdES-C in the present document.
Should both the signer and verifier be required to time-stamp the 
signature value to meet the requirements of the signature policy, the 
signature policy MAY specify a permitted time delay between the two 
time stamps.

C.4.4 Time-stamping for long life of signature before CA key 
compromises

Time-stamped extended electronic signatures are needed when there is a 
requirement to safeguard against the possibility of a CA key in the 
certificate chain ever being compromised.  A verifier may be required 
to provide on request, proof that the certification path and the 




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revocation information used a the time of the signature were valid, 
even in the case where one of the issuing keys or OCSP responder keys 
is later compromised.

The present document defines two ways of using time-stamps to protect 
against this compromise:

   - time-stamp the ES with Complete validation data, when an OCSP 
     response is used to get the status of the certificate from the 
     signer (CAdES-X Type 1).  This format is suitable to be used with 
     an OCSP response and offers the additional advantage to provide 
     an integrity protection over the whole data;

   - time-stamp only the certification path and revocation information 
     references when a CRL is used to get the status of the 
     certificate from the signer (CAdES-X Type2).  This format is 
     suitable to be used with CRLs, since the time-stamped information 
     may be used for more than one signature (when signers have their 
     certificates issued by the same CA and when signatures can be 
     checked using the same CRLs).

 NOTE: The signer, verifier or both may obtain the time-stamp.

C.4.4.1 Time-stamping the ES with complete validation data 
        (CAdES-X Type 1)

When an OCSP response is used, it is necessary to time stamp in 
particular that response in the case the key from the responder would 
be compromised.  Since the information contained in the OCSP response 
is user specific and time specific, an individual time stamp is needed 
for every signature received.  Instead of placing the time stamp only 
over the certification path references and the revocation information 
references, which include the OCSP response, the time stamp is placed 
on the CAdES-C.  Since the certification path and revocation 
information references are included in the ES with Complete validation 
data they are also protected.  For the same cryptographic price, this 
provides an integrity mechanism over the ES with Complete validation 
data.  Any modification can be immediately detected.  It should be 
noticed that other means of protecting/detecting the integrity of the 
ES with Complete Validation Data exist and could be used.
Although the technique requires a time stamp for every signature, it is 
well suited for individual users wishing to have an integrity protected 
copy of all the validated signatures they have received.

By time-stamping the complete electronic signature, including the 
digital signature as well as the references to the certificates and 
revocation status information used to support validation of that 
signature, the time-stamp ensures that there is no ambiguity in the 
means of validating that signature.





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This technique is referred to as CAdES-X Type 1 in the present 
document.

 NOTE: Trust is achieved in the references by including a hash of the 
       data being referenced.

If it is desired for any reason to keep a copy of the additional data 
being referenced, the additional data may be attached to the electronic 
signature, in which case the electronic signature becomes an CAdES-X 
Long Type 1 as defined by the present document.

An CAdES-X Long Type 1 is simply the concatenation of an CAdES-X Type 1 
with a copy of the additional data being referenced.

C.4.4.2 Time-stamping certificates and revocation information 
        references (CAdES-X Type 2)

Time-stamping each ES with Complete Validation Data as defined above 
may not be efficient, particularly when the same set of CA certificates 
and CRL information is used to validate many signatures.

Time-stamping CA certificates will stop any attacker from issuing bogus 
CA certificates that could be claimed to exist before the CA key was 
compromised.  Any bogus time-stamped CA certificates will show that the 
certificate was created after the legitimate CA key was compromised.  
In the same way, time-stamping CA CRLs, will stop any attacker from 
issuing bogus CA CRLs which could be claimed to exist before the CA key 
was compromised.

Time-stamping of commonly used certificates and CRLs can be done 
centrally, e.g. inside a company or by a service provider.  This method 
reduces the amount of data the verifier has to time-stamp, for example 
it could reduce to just one time stamp per day (i.e. in the case were 
all the signers use the same CA and the CRL applies for the whole day).  
The information that needs to be time stamped is not the actual 
certificates and CRLs but the unambiguous references to those 
certificates and CRLs.

This technique is referred to as CAdES-X Type 2 in the present document 
and requires the following:

   - all the CA certificates references and revocation information 
     references (i.e. CRLs) used in validating the CAdES-C are covered 
     by one or more time-stamp.

Thus an CAdES-C with a time-stamp signature value at time T1, can be 
proved valid if all the CA and CRL references are time-stamped at time 
T1+.






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C.4.5 Time-stamping for archive of signature

Advances in computing increase the probability of being able to break 
algorithms and compromise keys.  There is therefore a requirement to be 
able to protect electronic signatures against this possibility.

Over a period of time weaknesses may occur in the cryptographic 
algorithms used to create an electronic signature (e.g. due to the time 
available for crypto analysis, or improvements in crypto analytical 
techniques).  Before such weaknesses become likely, a verifier should 
take extra measures to maintain the validity of the electronic 
signature.  Several techniques could be used to achieve this goal 
depending on the nature of the weakened cryptography.  In order to 
simplify matters, a single technique, called Archive validation data, 
covering all the cases is being used in the present document.

Archive validation data consists of the validation data and the 
complete certificate and revocation data, time stamped together with 
the electronic signature.  The Archive validation data is necessary if 
the hash function and the crypto algorithms that were used to create 
the signature are no longer secure.  Also, if it cannot be assumed that 
the hash function used by the Time Stamping Authority is secure, then 
nested time-stamps of Archived Electronic Signature are required.

The potential for Trusted Service Provider (TSP) key compromise should 
be significantly lower than user keys, because TSP(s) are expected to 
use stronger cryptography and better key protection.  It can be 
expected that new algorithms (or old ones with greater key lengths) 
will be used.  In such a case, a sequence of time-stamps will protect 
against forgery.  Each time-stamp needs to be affixed before either the 
compromise of the signing key or of the cracking of the algorithms used 
by the TSA.  TSAs (Time-stamping Authorities) should have long keys 
(e.g. which at the time of drafting the present document was at least 
2048 bits for the signing RSA algorithm) and/or a "good" or different 
algorithm.

Nested time-stamps will also protect the verifier against key 
compromise or cracking the algorithm on the old electronic signatures.

The process will need to be performed and iterated before the 
cryptographic algorithms used for generating the previous time stamp 
are no longer secure.  Archive validation data may thus bear multiple 
embedded time stamps.

This technique is referred to as CAdES-A in the present document.








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C.4.6 Reference to additional data

Using CAdES-X Type 1 or CAdES-X Type 2 extended validation data 
verifiers still needs to keep track of all the components that were 
used to validate the signature, in order to be able to retrieve them 
again later on.  These components may be archived by an external source 
like a trusted service provider, in which case referenced information 
that is provided as part of the ES with Complete validation data 
(CAdES-C) is adequate.  The actual certificates and CRL information 
reference in the CAdES-C can be gathered when needed for arbitration.

If references to additional data are not adequate, then the actual 
values of all the certificates and revocation information required may 
be part of the electronic signature.  This technique is referred to as 
CAdES-X Long Type 1 or CAdES-X Long Type 2 in the present document.

C.4.7 Time-stamping for mutual recognition

In some business scenarios both the signer and the verifier need to 
time-stamp their own copy of the signature value.  Ideally the two 
time-stamps should be as close as possible to each other.

   EXAMPLE:  A contract is signed by two parties A and B representing 
             their respective organizations, to time-stamp the signer 
             and verifier data two approaches are possible:

                  - under the terms of the contract pre-defined common 
                    "trusted" TSA may be used;

                  - if both organizations run their own time-stamping 
                    services, A and B can have the transaction 
                    time-stamped by these two time-stamping services.

In the latter case, the electronic signature will only be considered as 
valid, if both time-stamps were obtained in due time (i.e. there should 
not be a long delay between obtaining the two time-stamps).  Thus, 
neither A nor B can repudiate the signing time indicated by their own 
time-stamping service.  Therefore, A and B do not need to agree on a 
common "trusted" TSA to get a valid transaction.

It is important to note that signatures may be generated "off-line" and 
time-stamped at a later time by anyone, e.g. by the signer or any 
recipient interested in validating the signature.  The time-stamp over 
the signature from the signer can thus be provided by the signer 
together with the signed document, and/or obtained by the verifier 
following receipt of the signed document.

The business scenarios may thus dictate that one or more of the long-
term signature time-stamping methods describe above be used.  This may 
be part of a mutually agreed Signature Validation Policy which is part 
of an agreed signature policy under which digital signature may be used 
to support the business relationship between the two parties.


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C.4.8 TSA key compromise

TSA servers should be built in such a way that once the private 
signature key is installed, there is minimal likelihood of compromise 
over as long as possible period.  Thus the validity period for the 
TSA's keys should be as long as possible.

Both the CAdES-T and the CAdES-C contain at least one time stamp over 
the signer's signature.  In order to protect against the compromise of 
the private signature key used to produce that time-stamp, the Archive 
validation data can be used when a different Time-Stamping Authority 
key is involved to produce the additional time-stamp.  If it is 
believed that the TSA key used in providing an earlier time-stamp may 
ever be compromised (e.g. outside its validity period), then the CAdES-
A should be used.  For extremely long periods this may be applied 
repeatedly using new TSA keys.

This technique is referred to as a nested CAdES-A in the present 
document.

C.5 Multiple signatures

Some electronic signatures may only be valid if they bear more than one 
signature.  This is the case generally when a contract is signed 
between two parties.  The ordering of the signatures may or may not be 
important, i.e. one may or may not need to be applied before the other.

Several forms of multiple and counter signatures need to be supported, 
which fall into two basic categories:

   - independent signatures;
   - embedded signatures.

Independent signatures are parallel signatures where the ordering of 
the signatures is not important.  The capability to have more than one 
independent signature over the same data shall be provided.

Embedded signatures are applied one after the other and are used where 
the order the signatures are applied is important.  The capability to 
sign over signed data shall be provided.

These forms are described in clause 5.13.  All other multiple signature 
schemes, e.g. a signed document with a countersignature, double 
countersignatures or multiple signatures, can be reduced to one or more 
occurrence of the above two cases.









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Annex D (informative):Data protocols to interoperate with TSPs

D.1 Operational protocols

The following protocols can be used by signers and verifiers to 
interoperate with Trusted Service Providers during the electronic 
signature creation and validation.

D.1.1 Certificate retrieval

User certificates, CA certificate and cross-certificates can be 
retrieved from a repository using the Lightweight Directory Access 
Protocol as defined in as defined RFC 2559 (see informative 
references), with the schema defined in RFC 2587 (see informative 
references).

D.1.2 CRL retrieval

Certificate revocation lists, including authority revocation lists and 
partial CRL variants, can be retrieved from a repository using the 
Lightweight Directory Access Protocol as defined in RFC 2559 (see 
informative references), with the schema defined in RFC 2587 (see 
informative references).

D.1.3 OnLine certificate status

As an alternative to use of certificate revocation lists the status of 
certificate can be checked using the OnLine Certificate Status Protocol 
(OCSP) as defined in RFC 2560 [3].

D.1.4 Time-stamping

The time-stamping service can be accessed using the Time-Stamping 
Protocol defined in RFC 3161 [7].

D.2 Management protocols

Signers and verifiers can use the following management protocols to 
manage the use of certificates.

D.2.1 Request for certificate revocation

Request for a certificate to be revoked can be made using the 
revocation request and response messages defined in 
RFC 2510 (see informative references).









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Annex E (informative): Guidance on naming

E.1 Allocation of names

The subject name shall be allocated through a registration scheme 
administered through a Registration Authority (RA) to ensure 
uniqueness.  This RA may be an independent body or a function carried 
out by the Certification Authority.

In addition to ensuring uniqueness, the RA shall verify that the name 
allocated properly identifies the applicant and that authentication 
checks are carried out to protect against masquerade.

The name allocated by an RA is based on registration information 
provided by, or relating to, the applicant (e.g. his personal name, 
date of birth, residence address) and information allocated by the RA.  
Three variations commonly exist:

   - the name is based entirely on registration information which 
     uniquely identifies the applicant (e.g. "Pierre Durand (born on) 
     July 6, 1956");

   - the name is based on registration information with the addition 
     of qualifiers added by the registration authority to ensure 
     uniqueness (e.g. "Pierre Durand 12");

   - the registration information is kept private by the registration 
     authority and the registration authority allocates a "pseudonym".

E.2 Providing access to registration information

Under certain circumstances it may be necessary for information used 
during registration, but not published in the certificate, to be made 
available to third parties (e.g. to an arbitrator to resolve a dispute 
or for law enforcement).  This registration information is likely to 
include personal and sensitive information. 

Thus the RA needs to establish a policy for:

   - whether the registration information should be disclosed;
   - to whom such information should be disclosed;
   - under what circumstances such information should be disclosed.

This policy may be different whether the RA is being used only within a 
company or for public use.  The policy will have to take into account 
national legislation and in particular any data protection and privacy 
legislation.








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Currently, the provision of access to registration is a local matter 
for the RA.  However, if open access is required, standard protocols 
such as HTTP - RFC 2068 (Internet Web Access Protocol) may be employed 
with the addition of security mechanisms necessary to meet the data 
protection requirements (e.g. Transport Layer Security - RFC 2246 with 
client authentication).

E.3 Naming schemes

E.3.1 Naming schemes for individual citizens

In some cases the subject name that is contained in a public key 
certificate may not be meaningful enough.  This may happen because of 
the existence of homonyms or because of the use of pseudonyms.  A 
distinction could be made if more attributes were present.  However, 
adding more attributes to a public key certificate placed in a public 
repository would be going against the privacy protection requirements. 

In any case the Registration Authority will get information at the time 
of registration but not all that information will be placed in the 
certificate.  In order to achieve a balance between these two opposite 
requirements the hash values of some additional attributes can be 
placed in a public key certificate.  When the certificate owner 
provides these additional attributes, then they can be verified.  Using 
biometrics attributes may unambiguously identify a person.  Example of 
biometrics attributes that can be used include: a picture or a manual 
signature from the certificate owner. 

 NOTE: Using hash values protects privacy only if the possible inputs 
       are large enough.  For example, using the hash of a person's 
       social security number is generally not sufficient since it 
       can easily be reversed.

A picture can be used if the verifier once met the person and later on 
wants to verify that the certificate that he or she got relates to the 
person whom was met.  In such a case, at the first exchange the picture 
is sent and the hash contained in the certificate may be used by the 
verifier to verify that it is the right person.  At the next exchange 
the picture does not need to be sent again. 

A manual signature may be used if a signed document has been received 
beforehand.  In such a case, at the first exchange the drawing of the 
manual signature is sent and the hash contained in the certificate may 
be used by the verifier to verify that it is the right manual 
signature.  At the next exchange the manual signature does not need to 
be sent again.







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E.3.2 Naming schemes for employees of an organization

The name of an employee within an organization is likely to be some 
combination of the name of the organization and the identifier of the 
employee within that organization.

An organization name is usually a registered name, i.e. business or 
trading name used in day to day business.  This name is registered by a 
Naming Authority, which guarantees that the organization's registered 
name is unambiguous and cannot be confused with another organization.  
In order to get more information about a given registered organization 
name, it is necessary to go back to a publicly available directory 
maintained by the Naming Authority.

The identifier may be a name or a pseudonym (e.g. a nickname or a 
employee number).  When it is a name, it is supposed to be descriptive 
enough to unambiguously identify the person.  When it is a pseudonym, 
the certificate does not disclose the identity of the person.  However 
it ensures that the person has been correctly authenticated at the time 
of registration and therefore may be eligible to some advantages 
implicitly or explicitly obtained through the possession of the 
certificate.  In either case, however, this can be insufficient because 
of the existence of homonyms.

Placing more attributes in the certificate may be one solution, for 
example by giving the organization unit of the person or the name of a 
city where the office is located.  However the more information is 
placed in the certificate the more problems arise if there is a change 
in the organization structure or the place of work.  So this may not be 
the best solution.  An alternative is to provide more attributes (like 
the organization unit and the place of work) through access to a 
directory maintained by the company.  It is likely that at the time of 
registration the Registration Authority got more information than what 
was placed in the certificate, if such additional information is placed 
in a repository accessible only to the organization.


















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Annex F (informative): Example structured contents and MIME

F.1 General description

The signed content may be structured as using MIME (Multipurpose 
Internet Mail Extensions - RFC 2045 [6].  Whilst the MIME structure was 
initially developed for Internet e-mail, it has a number of features 
which make it useful to provide a common structure for encoding a range 
of electronic documents and other multi-media data (e.g. photographs, 
video).  These features include:

   - it provides a means of signalling the type of "object" being 
     carried (e.g. text, image, ZIP file, application data);

   - it provides a means of associating a file name with an object;

   - it can associate several independent "objects" (e.g. a document 
     and image) to form a multi-part object;

   - it can handle data encoded in text or binary and, if necessary, 
     re-encode the binary as text.

When encoding a single object MIME consists of:

   - header information, followed by;
   - encoded content.

This structure can be extended to support multi-part content.

F.2 Header information

A MIME header includes:

MIME Version information:
e.g.: MIME-Version: 1.0

Content type information which includes information describing the 
content sufficient for it to presented to a user or application process 
as required.  This includes information on the "media type" (e.g. text, 
image, audio) or whether the data is for passing to a particular type 
of application.  In the case of text the content type includes 
information on the character set used.

e.g. Content-Type: text/plain; charset="us-ascii"

Content encoding information, which defines how the content is encoded. 
(See below about encoding supported by MIME).

Other information about the content such as a description, or an 
associated file name.




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An example MIME header for text object is:

Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

An example MIME header for a binary file containing a word document is:

Content-Type: application/octet-stream
Content-Transfer-Encoding: base64
Content-Description: JCFV201.doc (Microsoft Word Document)
Content-Disposition: filename="JCFV201.doc"

F.3 Content encoding

MIME supports a range of mechanisms for encoding the both text and 
binary data.

Text data can be carried transparently as lines of text data encoded in 
7 or 8 bit ASCII characters.  MIME also includes a "quoted-printable" 
encoding which converts characters other than the basic ASCII into an 
ASCII sequence.

Binary can either be carried:

   - transparently a 8 bit octets; or
   - converted to a basic set of characters using a system called 
     Base64.

 NOTE: As there are some mail relays which can only handle 7 bit 
       ASCII, Base64 encoding is usually used on the Internet.

F.4 Multi-part content

Several objects (e.g. text and a file attachment) can be associated 
together using a special "multi-part" content type.  This is indicated 
by the content type "multipart" with an indication of the string to be 
used indicate a separation between each part.

In addition to a header for the overall multipart content, each part 
includes its own header information indicating the inner content type 
and encoding.


An example of a multipart content is:

Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="----
=_NextPart_000_01BC4599.98004A80"
Content-Transfer-Encoding: 7bit




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------=_NextPart_000_01BC4599.98004A80
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

Per your request, I've attached our proposal for the Java Card Version 
2.0 API and the Java Card FAQ.

------=_NextPart_000_01BC4599.98004A80
Content-Type: application/octet-stream; name="JCFV201.doc"
Content-Transfer-Encoding: base64
Content-Description: JCFV201.doc (Microsoft Word Document)
Content-Disposition: attachment; filename="JCFV201.doc"

0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAACAAAAAgAAAAA
AAAAAEAAAtAAAAAEAAAD+////AAAAAAMAAAAGAAAA//////////////////////////////
//////////AANhAAQAYg==

------=_NextPart_000_01BC4599.98004A80--

Multipart content can be nested.  So a set of associated objects (e.g. 
HTML text and images) can be handled as a single attachment to another 
object (e.g. text).

F.5 S/MIME

Previous clauses in this annex have described the use of MIME to encode 
data.  MIME encoded data can be signed (i.e. carried in the eContent of 
the SignedData structure) thereby signalling the type of information 
that has been signed. 

MIME can also be used to encode the CMS structure containing data after 
it has been signed so that, for example, this can be carried within an 
e-mail message.  The specific use of MIME to carry CMS (extended as 
defined in the present document) secured data is called S/MIME.  The 
relationship between the general use of MIME for encoding content, CMS 
and S/MIME is illustrated in figure F.1.


 +------------++-------------++----------++------------++------------+
 |            ||             ||          ||            ||            |
 |  E-mail    ||   S/MIME    ||  CAdES   ||   MIME     || Word file  |
 |            ||             ||          ||            ||            |
 |From: Smith ||Content Type=||SignedData||ContentType=||Dear MrSmith|
 |To:Jones    ||application/ || Econtent ||application/||Received    |
 |Subject:    ||pkcs7        ||          ||octet-stream||  100 tins  |
 |Signed doc. ||             ||          ||            ||            |
 |       /|   ||        /|   ||     /|   ||       /|   ||  Mr.Jones  |
 |      / -----+       / -----+    / -----+      / -----+            |
 |      \ -----+       \ -----+    \ -----+      \ -----+            |
 |       \|   ||        \|   ||     \|   ||       \|   ||            |
 |            |+------------- |          |+------------+|            |
 +------------+              ++----------+              +------------+

                             Figure F.1

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S/MIME carries electronic signatures as either:

   - an "application/pkcs7-mime" object with the CMS carried as binary 
     attachment (PKCS7 is the name of the early version of CMS).

An example of signed data encoded using this approach is: 
Content-Type: application/pkcs7-mime; smime-type=signed-data;
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename=smime.p7m

  567GhIGfHfYT6ghyHhHUujpfyF4f8HHGTrfvhJhjH776tbB9HG4VQbnj7
  77n8HHGT9HG4VQpfyF467GhIGfHfYT6rfvbnj756tbBghyHhHUujhJhjH
  HUujhJh4VQpfyF467GhIGfHfYGTrfvbnjT6jH7756tbB9H7n8HHGghyHh
  6YT64V0GhIGfHfQbnj75

This approach is similar to handling signed data as any other binary 
file attachment.  Thus, this encoding can be used where signed data 
passes through gateways to other e-mail systems (e.g. those based on 
other e-mail systems).
A "multipart/signed" object with the signed data and the signature 
encoded as separate MIME objects.

An example of signed data encoded this approach is:
Content-Type: multipart/signed;
          protocol="application/pkcs7-signature";
          micalg=sha1; boundary=boundary42

       --boundary42
       Content-Type: text/plain

       This is a clear-signed message.

       --boundary42
       Content-Type: application/pkcs7-signature; name=smime.p7s
       Content-Transfer-Encoding: base64
       Content-Disposition: attachment; filename=smime.p7s

       ghyHhHUujhJhjH77n8HHGTrfvbnj756tbB9HG4VQpfyF467GhIGfHfYT6
       4VQpfyF467GhIGfHfYT6jH77n8HHGghyHhHUujhJh756tbB9HGTrfvbnj
       n8HHGTrfvhJhjH776tbB9HG4VQbnj7567GhIGfHfYT6ghyHhHUujpfyF4
       7GhIGfHfYT64VQbnj756

       --boundary42--












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With this second approach MIME the signed data passes through the CMS 
process and is carried as part of the S/MIME structure as illustrated 
in figure F.2.  The CMS structure just holds the electronic signature.


 +------------++-------------++----------++------------++------------+
 |            ||             ||          ||            ||            |
 |  E-mail    ||  | /MIME    ||  CAdES   ||   MIME     || Word file  |
 |            ||             ||          ||            ||            |
 |From: Smith ||Content Type=||SignedData||ContentType=||Dear MrSmith|
 |To:Jones    ||multipart/   ||          ||application/||Received    |
 |Subject:    ||signed       ||          ||octet-stream||  100 tins  |
 |Signed doc. ||        /|   ||          ||            ||            |
 |       /|   ||       / -----------------+       /|   ||  Mr.Jones  |
 |      / -----+       \ -----------------+      / -----+            |
 |      \ -----+        \|   ||          ||      \ -----+            |
 |       \|   ||ContentType= ||          ||       \|   ||            |
 +------------+|application/ ||          |+------------+|            |
               |octet-stream ||          |              +------------+
               |             ||          |
               |ContentType= ||          |
               |application/ ||          |
               |pkcs7-       ||          |
               |signature    ||          |
               |        /|   ||          |
               |       / -----+          |
               |       \ -----+          |
               |        \|   ||----------+
               |             |
               +-------------+

                                Figure F.2


The second approach (multipart/signed) has the advantage that the 
signed data can be decoded by any MIME compatible e-mail system even if 
it does not recognize CMS encoded electronic signatures.  However, this 
form cannot be used with other e-mail systems.















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Annex G (informative): Relationship to the European Directive and EESSI 

G.1 Introduction

This annex provides an indication of the relationship between 
electronic signatures created under the present document and 
requirements under the European Parliament and Council Directive on a 
Community framework for electronic signatures. 

 NOTE: Legal advice should be sought on the specific national 
       legislation regarding use of electronic signatures.

The present document is one of a set of standards being defined under 
the "European Electronic Signature Standardization Initiative" (EESSI) 
for electronic signature products and solutions compliant with the 
European Directive for electronic signatures.

G.2 Electronic signatures and the directive

This directive defines electronic signatures as:

   - "data in electronic form which are attached to or logically 
     associated with other electronic data and which serve as a method 
     of authentication".

The directive states that an electronic signature should not be denied 
"legal effectiveness and admissibility as evidence in legal 
proceedings" solely on the grounds that it is in electronic form.

The directive identifies an electronic signature as having equivalence 
to a hand-written signature if it meets specific criteria:

   - it is an "advanced electronic signature" with the following 
     properties: 

        a) it is uniquely linked to the signatory;

        b) it is capable of identifying the signatory;

        c) it is created using means that the signatory can maintain 
           under his sole control; and

        d) it is linked to the data to which it relates in such a 
           manner that any subsequent change of the data is detectable.

   - it is based on a certificate which meets detailed criteria given 
     in annex I to the directive and is issued by a "certification-
     service-provider" which meets requirements given in annex II to 
     the directive.  Such a certificate is referred to as a "qualified 
     certificate";




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   - it is created by a "device" which detailed criteria given in 
     annex III to the directive.  Such a device is referred to a 
     "secure-signature-creation device";

This form of electronic signature is referred to as a "qualified 
electronic signature" in EESSI (see below).

G.3 ETSI electronic signature formats and the directive
An electronic signature created in accordance with the present document 
is:

   a) considered to be an "electronic signature" under the terms of 
      the Directive;

   b) considered to be an "advanced electronic signature" under the 
      terms of the Directive;

   c) considered to be a "Qualified Electronic Signature" provided the 
      additional requirements in annex I, II and III of the Directive 
      are met.  The requirements in annex I, II and III of the 
      Directive are outside the scope of the present document, and are 
      subject to further standardization.

G.4 EESSI standards and classes of electronic signature

G.4.1 Structure of EESSI standardization

EESSI looks at standards in several areas.  See the ETSI ESI and CEN 
web sites for the latest list of standards and their versions

   - use of X.509 public key certificates as qualified certificates;

   - security Management and Certificate Policy for CSPs Issuing 
     Qualified Certificates;

   - security requirements for trustworthy systems used by CSPs 
     Issuing Qualified Certificates;

   - security requirements for Secure Signature Creation Devices;

   - security requirements for Signature Creation Systems;

   - procedures for Electronic Signature Verification;

   - electronic signature syntax and encoding formats;

   - protocol to interoperate with a Time Stamping Authority;

   - Policy requirements for Time-Stamping Authorities;

   - XML electronic signature formats.



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Each of these standards addresses a range of requirements including the 
requirements of Qualified Electronic Signatures as specified in article 
5.1 of the Directive.  However, some of them also address general 
requirements of electronic signatures for business and electronic 
commerce which all fall into the category of article 5.2 of the 
Directive.  Such variation in the requirements may be identified either 
as different levels or different options.

G.4.2 Classes of electronic signatures

Since some of these standards address a range of requirements, it may 
be useful to identify a set of standards to address a specific business 
need.  Such a set of standards and their uses defines a class of 
electronic signature.  The first class already identified is the 
qualified electronic signature, fulfilling the requirements of article 
5.1 of the Directive.

A limited number of "classes of electronic signatures" and 
corresponding profiles could be defined by EESSI, in close co-operation 
with actors on the market (business, users, suppliers).  Need for such 
standards is envisaged, in addition to those for qualified electronic 
signatures, in areas such as:

   - different classes of electronic signatures with long term 
     validity;

   - electronic signatures for business transactions with limited 
     value.

G.4.3 EESSI classes and the ETSI electronic signature format
The electronic signature format defined in the present document is 
applicable to the EESSI area "electronic signature and encoding 
formats".

An electronic signature produced by a signer (see clause 5 and 
conformance clause 10.1) is applicable to the proposed class of 
electronic signature: "qualified electronic signatures fulfilling 
article 5.1".

With the addition of validation data by the verifier (see clause 6 and 
conformance clause 10.2) this would become applicable electronic 
signatures adding long-term validity attributes to the qualified 
electronic signature.


Annex H (informative):APIs for the generation and verification of 
electronic signatures tokens

While the present document describes the data format of an electronic 
signature, the question is whether there exists APIs (Application 
Programming Interfaces) able to manipulate these structures.  At least 
two such APIs have been defined.  One set by the IETF and another set 
by the OMG (Object Management Group).

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H.1 Data framing

In order to be able to use either of these APIs, it will be necessary 
to frame the previously defined electronic signature data structures 
using a mechanism-independent token format.  Clause 3.1 of RFC 2743 
(see informative references) describes that framing incorporating an 
identifier of the mechanism type to be used and enabling tokens to be 
interpreted unambiguously.

In order to be processable by these APIs, all electronic signature data 
formats that are defined in the present document shall be framed 
following that description.

The encoding format for the token tag is derived from ASN.1 and DER, 
but its concrete representation is defined directly in terms of octets 
rather than at the ASN.1 level in order to facilitate interoperable 
implementation without use of general ASN.1 processing code.  The token 
tag consists of the following elements, in order:

   1) 0x60 -- Tag for RFC 2743 SEQUENCE; indicates that constructed 
      form, definite length encoding follows.

   2) Token length octets, specifying length of subsequent data (i.e. 
      the summed lengths of elements 3 to 5 in this list, and of the 
      mechanism-defined token object following the tag).  This element 
      comprises a variable number of octets:

     a) If the indicated value is less than 128, it shall be 
        represented in a single octet with bit 8 (high order) set to 
        "0" and the remaining bits representing the value.

     b) If the indicated value is 128 or more, it shall be represented 
        in two or more octets, with bit 8 of the first octet set to 
        "1" and the remaining bits of the first octet specifying the 
        number of additional octets.  The subsequent octets carry the 
        value, 8 bits per octet, most significant digit first.  The 
        minimum number of octets shall be used to encode the length 
        (i.e. no octets representing leading zeros shall be included 
        within the length encoding).

   3) 0x06 -- Tag for OBJECT IDENTIFIER.

   4) Object identifier length -- length (number of octets) of the 
      encoded object identifier contained in element 5, encoded per 
      rules as described in 2a) and 2b) above.

   5) object identifier octets -- variable number of octets, encoded 
      per ASN.1 BER rules:






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      - The first octet contains the sum of two values:

          (1) the top-level object identifier component, multiplied by 
           40 (decimal); and

          (2) the second-level object identifier component.

           This special case is the only point within an object 
           identifier encoding where a single octet represents contents 
           of more than one component.

      - Subsequent octets, if required, encode successively-lower 
        components in the represented object identifier.  A 
        component's encoding may span multiple octets, encoding 7 bits 
        per octet (most significant bits first) and with bit 8 set to 
        "1" on all but the final octet in the component's encoding.  
        The minimum number of octets shall be used to encode each 
        component (i.e. no octets representing leading zeros shall be 
        included within a component's encoding).

  NOTE: In many implementations, elements 3 to 5 may be stored and 
        referenced as a contiguous string constant.

The token tag is immediately followed by a mechanism-defined token 
object.  Note that no independent size specifier intervenes following 
the object identifier value to indicate the size of the mechanism- 
defined token object.

Tokens conforming to the present document shall have the following OID 
in order to be processable by IDUP-APIs:

id-etsi-es-IDUP-Mechanism-v1 OBJECT IDENTIFIER ::=
 { itu-t(0) identified-organization(4) etsi(0) 
  electronic-signature-standard (1733) part1 (1) IDUPMechanism (4) 
  etsiESv1(1) }

H.2 IDUP-GSS-APIs defined by the IETF

The IETF CAT WG has produced in December 1998 an RFC (RFC 2479 - see 
informative references) under the name of IDUP-GSS-API (Independent 
Data Unit Protection) able to handle the electronic signature data 
format defined in the present document.

The IDUP-GSS-API includes support for non-repudiation services.

It supports evidence generation, where "evidence" is information that 
either by itself, or when used in conjunction with other information, 
is used to establish proof about an event or action, as well a evidence 
verification.





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IDUP supports various types of evidences.  All the types defined in 
IDUP are supported in the present document through the commitment type 
parameter.

Clause 2.3.3 of IDUP describes the specific calls needed to handle 
evidences ("EV" calls).  The "EV" group of calls provides a simple, 
high-level interface to underlying IDUP mechanisms when application 
developers need to deal only with evidences but not with encryption or 
integrity services.

All generations and verification are performed according to the content 
of a NR policy that is referenced in the context.

Get_token_details is used to return to an application the attributes 
that correspond to a given input token.  Since IDUP-GSS- API tokens are 
meant to be opaque to the calling application, this function allows the 
application to determine information about the token without having to 
violate the opaqueness intention of IDUP.  Of primary importance is the 
mechanism type, which the application can then use as input to the 
IDUP_Establish_Env() call in order to establish the correct environment 
in which to have the token processed.

Generate_token generates a non-repudiation token using the current 
environment.

Verify_evidence verifies the evidence token using the current 
environment.  This operation returns a major_status code which can be 
used to determine whether the evidence contained in a token is complete 
(i.e. can be successfully verified (perhaps years) later).  If a 
token's evidence is not complete, the token can be passed to another 
API: form_complete_pidu to complete it.  This happens when a status 
"conditionally valid" is returned.  That status corresponds to the 
status "validation incomplete" of the present document.

Form_complete_PIDU is used primarily when the evidence token itself 
does not contain all the data required for its verification and it is 
anticipated that some of the data not stored in the token may become 
unavailable during the interval between generation of the evidence 
token and verification unless it is stored in the token.  The 
Form_Complete_PIDU operation gathers the missing information and 
includes it in the token so that verification can be guaranteed to be 
possible at any future time.

H.3 CORBA security interfaces defined by the OMG

Non-repudiation interfaces have been defined in "CORBA Security", a 
document produced by the OMG (Object Management Group).  These 
interfaces are described in IDL (Interface Definition Language) and are 
optional. 





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The handling of "tokens" supporting non-repudiation is done through the 
following interfaces:

   - set_NR_features specifies the features to apply to future 
     evidence generation and verification operations;

   - get_NR_features returns the features which will be applied to 
     future evidence generation and verification operations;

   - generate_token generates a Non-repudiation token using the 
     current Non-repudiation features;

   - verify_evidence verifies the evidence token using the current 
     Non-repudiation features;
   - get_tokens_details returns information about an input Non-
     repudiation token.  The information returned depends upon the 
     type of token;

   - form_complete_evidence is used when the evidence token itself 
     does not contain all the data required for its verification, and 
     it is anticipated that some of the data not stored in the token 
     may become unavailable during the interval between generation of 
     the evidence token and verification unless it is stored in the 
     token.  The form_complete_evidence operation gathers the missing 
     information and includes it in the token so that verification can 
     be guaranteed to be possible at any future time.

  NOTE: The similarity between the two sets of APIs is noticeable.


























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Annex I (informative):Cryptographic algorithms


RFC 3370 [10] describes the conventions for using several cryptographic 
algorithms with the Crytographic Message Syntax (CMS).  Only the 
hashing and signing algorithms are appropriate for use with the present 
document.

Since the publication of RFC 3370 [10], MD5 has been broken.  This 
algorithm is no more considered as appropriate and has been deleted 
from the list of algorithms.

I.1 Digest algorithms

I.1.1 SHA-1

The SHA-1 digest algorithm is defined in FIPS Pub 180-1.  The algorithm 
identifier for SHA-1 is:

sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) oiw(14) 
secsig(3) algorithm(2) 26 }

The AlgorithmIdentifier parameters field is optional.  If present, the 
parameters field shall contain an ASN.1 NULL.  Implementations should 
accept SHA-1 AlgorithmIdentifiers with absent parameters as well as 
NULL parameters.  Implementations should generate SHA-1 
AlgorithmIdentifiers with NULL parameters.

I.1.2 General

The following is a selection of work that has been done in the area of 
digest algorithms or, as they are often called, hash functions:

   - ISO/IEC 10118-1 (1994): "Information technology - Security 
     techniques - Hash-functions - Part 1: General".  ISO/IEC 10118-1 
     contains definitions and describes basic concepts.

   - ISO/IEC 10118-2 (1994): "Information technology - Security 
     techniques - Hash-functions - Part 2: Hash-functions using an n-
     bit block cipher algorithm".  ISO/IEC 10118-2 specifies two ways 
     to construct a hash-function from a block cipher.

   - ISO/IEC 10118-3 (1997): "Information technology - Security 
     techniques - Hash-functions - Part 3: Dedicated hash-functions". 
     ISO/IEC 10118-3 specifies the following dedicated hash-functions:

         - SHA-1 (FIPS 180-1);
         - RIPEMD-128;
         - RIPEMD-160.






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   - ISO/IEC 10118-4 (1998): "Information technology - Security 
     techniques - Hash-functions - Part 4: Hash-functions using 
     modular arithmetic".

   - RFC 1320 (PS 1992): "The MD4 Message-Digest Algorithm".  RFC 1320 
     specifies the hash-function MD4.  Today, MD4 is considered out-
     dated.

   - RFC 1321 (I 1992): "The MD5 Message-Digest Algorithm".  RFC 1321 
      (informational) specifies the hash-unction MD5.

   - FIPS Publication 180-1 (1995): "Secure Hash Standard". FIPS 180-1
     specifies the Secure Hash Algorithm (SHA), dedicated hash-
     function developed for use with the DSA.  The original SHA 
     published in 1993 was slightly revised in 1995 and renamed SHA-1.

   - ANSI X9.30-2 (1997): "Public Key Cryptography for the Financial 
     Services Industry - Part 2: The Secure Hash Algorithm (SHA-1)".  
     X9.30-2 specifies the ANSI-Version of SHA-1.

   - ANSI X9.31-2 (1996): "Public Key Cryptography Using Reversible 
     Algorithms for the Financial Services Industry - Part 2: Hash 
     Algorithms".  X9.31-2 specifies hash algorithms.

I.2 Digital signature algorithms

I.2.1 DSA

The DSA signature algorithm is defined in FIPS Pub 186.  DSA is always 
used with the SHA-1 message digest algorithm.  The algorithm identifier 
for DSA is:

id-dsa-with-sha1 OBJECT IDENTIFIER ::=  { iso(1) member-body(2) us(840) 
x9-57 (10040) x9cm(4) 3 }

The AlgorithmIdentifier parameters field shall not be present.

I.2.2 RSA

The RSA signature algorithm is defined in RFC 2437 (see informative 
references).  RFC 3370 [10] specifies the use of the RSA signature 
algorithm with the SHA-1 algorithm.  The algorithm identifier for RSA 
with SHA-1 is:

Sha1WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) 
us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 5 }

 NOTE: RFC 3370 [10] recommends that MD5 is not used for new 
       implementations.





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I.2.3 General

The following is a selection of work that has been done in the area of 
digital signature mechanisms:

   - FIPS Publication 186 (1994): "Digital Signature Standard".  
     NIST's Digital Signature Algorithm (DSA) is a variant of 
     ElGamal's Discrete Logarithm based digital signature mechanism.  
     The DSA requires a 160-bit hash-function and mandates SHA-1.

   - IEEE P1363 (2000): "Standard Specifications for Public-Key 
     Cryptography".  IEEE P1363 contains mechanisms for digital 
     signatures, key establishment, and encipherment based on three 
     families of public-key schemes:

   - "Conventional" Discrete Logarithm (DL) based techniques, i.e. 
     Diffie-Hellman (DH) key agreement, Menezes-Qu-Vanstone (MQV) 
     key agreement, the Digital Signature Algorithm (DSA), and 
     Nyberg-Rueppel (NR) digital signatures;

   - Elliptic Curve (EC) based variants of the DL-mechanisms 
     specified above, i.e. EC-DH, EC-MQV, EC-DSA, and EC-NR.  For 
     elliptic curves, implementation options include mod p and 
     characteristic 2 with polynomial or normal basis 
     representation;

   - Integer Factoring (IF) based techniques including RSA 
     encryption, RSA digital signatures, and RSA-based key 
     transport.

   - ISO/IEC 9796 (1991): "Information technology - Security 
     techniques - Digital signature scheme giving message recovery".  
     ISO/IEC 9796 specifies a digital signature mechanism based on the 
     RSA public-key technique and a specifically designed redundancy 
     function.

   - ISO/IEC 9796-2 (1997): "Information technology - Security 
     techniques - Digital signature schemes giving message recovery - 
     Part 2: Mechanisms using a hash-function".  ISO/IEC 9796-2 
     specifies digital signature mechanisms with partial message 
     recovery that are also based on the RSA technique but make use of 
     a hash-function.

   - ISO/IEC 9796-4 (1998): "Digital signature schemes giving message 
     recovery - Part 4: Discrete logarithm based mechanisms".  ISO/IEC 
     9796-4 specifies digital signature mechanisms with partial 
     message recovery that are based on Discrete Logarithm techniques.  
     The document includes the Nyberg-Rueppel scheme.

   - ISO/IEC 14888-1: "Digital signatures with appendix - Part 1: 
     General".  ISO/IEC 14888-1 contains definitions and describes the 
     basic concepts of digital signatures with appendix.


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   - ISO/IEC 14888-2: "Digital signatures with appendix - Part 2: 
     Identity-based mechanisms".  ISO/IEC 14888-2 specifies digital 
     signature schemes with appendix that make use of identity-based 
     keying material.  The document includes the zero-knowledge 
     techniques of Fiat-Shamir and Guillou-Quisquater.

   - ISO/IEC 14888-3: "Digital signatures with appendix - Part 3: 
     Certificate-based mechanisms".  ISO/IEC 14888-3 specifies digital 
     signature schemes with appendix that make use of certificate-
     based keying material.  The document includes five schemes:

          - DSA;
          - EC-DSA, an elliptic curve based analog of NIST's Digital 
            Signature Algorithm;
          - Pointcheval-Vaudeney signatures;
          - RSA signatures;
          - ESIGN.

   - ISO/IEC 15946-2 (2002) : "Cryptographic techniques based on 
     elliptic curves - Part 2: Digital signatures". 

   - ISO/IEC 15946-3 (2002) specifies digital signature schemes with 
     appendix using elliptic curves.

   - The document includes two schemes:

          - EC-DSA, an elliptic curve based analog of NIST's Digital 
            Signature Algorithm;

          - EC-AMV, an elliptic curve based analog of the Agnew-Muller-
            Vanstone signature algorithm.

   - ANSI X9.31-1 (1997): "Public Key Cryptography Using Reversible 
     Algorithms for the Financial Services Industry - Part 1: The RSA 
     Signature Algorithm".  ANSI X9.31-1 specifies a digital signature 
     mechanism with appendix using the RSA public-key technique.

   - ANSI X9.30-1 (1997): "Public Key Cryptography Using Irreversible 
     Algorithms for the Financial Services Industry - Part 1: The 
     Digital Signature Algorithm (DSA)".  ANSI X9.30-1 specifies the 
     DSA, NIST's Digital Signature Algorithm.  

   - ANSI X9.62 (1998): "Public Key Cryptography for the Financial 
     Services Industry - The Elliptic Curve Digital Signature 
     Algorithm (ECDSA)".  ANSI X9.62 specifies the Elliptic Curve 
     Digital Signature Algorithm, an analog of NIST's Digital 
     Signature Algorithm (DSA) using elliptic curves.  The appendices 
     provide tutorial information on the underlying mathematics for 
     elliptic curve cryptography and many examples.





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Annex J (informative): Changes from the previous version 

   The title of the document has changed to be aligned with the title 
   of XAdES, the vocabulary used within the present document has been 
   aligned with the vocabulary used in XAdES,

   In the previous version of TS 101 733 (i.e. version 1.5.1) 
   sigPolicyHash was mandatory.  Implementations requiring to be 
   backward compatible with version 1.5.1 and previous versions 
   of the current document MUST include SigPolicyHash.

   The OIDs from the ASN.1 modules have changed for the following 
   reasons:

    - the OIDs of the ASN.1 modules of RFC 2560 and RFC 3161 have been 
      included.

    - since RFC 2459 and RFC 3369 has been obsoleted by RFC 3280 and 
      RFC 3852 respectively, there was the need to refer to the OIDs 
      of the ASN.1 modules of RFC 3280 and RFC 3852, instead of the 
      OIDs of the ASN.1 modules of RFC 2459 and RFC 3369.

    - the other change is related to the field sigPolicyHash from 
      SignaturePolicyId (see clause 5.8.1). That field was mandatory 
      and is now optional.





























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Full Copyright Statement

   Copyright (C) The Internet Society (2005).

   The contents of this Informational RFC amounts to a transposition of 
   the ETSI TS 101 733 V.1.6.3 and is technically equivalent to it.  
   The ETSI TS is under the ETSI Copyright (C). Individual copies of 
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   Information on the ETSI Intellectual Property Rights Policy may be 
   obtained from <http://www.etsi.org/legal/home.htm>. The document is 
   an extract from Annex 6 of the ETSI Rules of Procedure that are 
   available at : <http://portal.etsi.org/directives/home.asp>.

   The ETSI IPR database http://webapp.etsi.org/IPR/home.asp contains 
   IPRs, particularly patents and patent applications, which have been 
   notified to ETSI as being essential, or potentially essential, to 
   ETSI standards. Unless otherwise specified, all IPRs contained 
   herein have been notified to ETSI, with an undertaking from the 
   owner to grant licenses according to the terms and conditions of 
   Article 6.1 of Annex 6 of the ETSI Rules of the ETSI IPR Policy.

   The ETSI IPR database provides data that is based on the information 
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   Potential Licensees should use the information in this database at 
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