S/MIME WG S. Turner Internet Draft IECA, Inc. Intended Status: Standard Track July 25, 2007 Expires: January 25, 2008 Using SHA2 Algorithms with Cryptographic Message Syntax draft-ietf-smime-sha2-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on January 25, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes the conventions for using the message digest algorithms SHA-224, as defined in [RFC3874], and SHA-256, SHA-384, SHA-512, as defined in [SHA2], with the Cryptographic Message Syntax (CMS) [RFC3852]. It also describes the conventions for using these algorithms with CMS and the DSA, RSA, and ECDSA signature algorithms. Turner Expires January 25, 2008 [Page 1] Internet-Draft Using SHA2 Algorithms with CMS July 2007 Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Table of Contents 1. Introduction...................................................2 2. Message Digest Algorithms......................................3 2.1. SHA-224...................................................4 2.2. SHA-256...................................................4 2.3. SHA-384...................................................4 2.4. SHA-512...................................................4 3. Signature Algorithms...........................................5 3.1. DSA.......................................................5 3.2. RSA.......................................................6 3.3. ECDSA.....................................................6 4. Security Considerations........................................7 5. IANA Considerations............................................7 6. References.....................................................7 6.1. Normative References......................................7 6.2. Informative References....................................8 1. Introduction This document specifies the algorithm identifiers and specifies parameters for the message digest algorithms SHA-224, SHA-256, SHA- 384, and SHA-512 for use with the Cryptographic Message Syntax (CMS) [RFC3852]. The message digest algorithms are defined in [RFC3874] and [SHA2]. If an implementation chooses to support one of the algorithms discussed in this document, then the implementation MUST do so as described in this document. This document also specifies the algorithm identifier and parameters for use of SHA-224, SHA-256, SHA-384, and SHA-512 with DSA, RSA, and ECDSA. If an implementation chooses to support one of the algorithms discussed in this document, then the implementation MUST do so as described in this document. This document does not define new identifiers; they are taken from [RFC3874], [RFC4055], [ECCADD], [RFC3278], and [RFC3370]. Additionally, the parameters follow the conventions specified therein. Therefore, there is no ASN.1 module included in this document. Turner Expires January 25, 2008 [Page 2] Internet-Draft Using SHA2 Algorithms with CMS July 2007 Note that [RFC4231] specifies the conventions for use of for the message authentication code (MAC) algorithms: HMAC with SHA-224, HMAC with SHA-256, HMAC with SHA-384, and HMAC with SHA-512. 2. Message Digest Algorithms Digest algorithm identifiers are located in the SignedData digestAlgorithms field, the SignerInfo digestAlgorithm field, the DigestedData digestAlgorithm field, and the AuthenticatedData digestAlgorithm field. Digest values are located in the DigestedData digest field and the Message Digest authenticated attribute. In addition, digest values are input to signature algorithms. In CMS, the digest algorithm identifiers use the AlgorithmIdentifier syntax, which is included here for convenience: AlgorithmIdentifier ::= SEQUENCE { algorithm OBJECT IDENTIFIER, parameters ANY DEFINED BY algorithm OPTIONAL } The algorithm field is discussed in Sections 2.1-2.4 for each message digest algorithm. The following addresses the parameters field: There are two possible encodings for the SHA AlgorithmIdentifier parameters field. The two alternatives arise from the fact that when the 1988 syntax for AlgorithmIdentifier was translated into the 1997 syntax, the OPTIONAL associated with the AlgorithmIdentifier parameters got lost. Later the OPTIONAL was recovered via a defect report, but by then many people thought that algorithm parameters were mandatory. Because of this history some implementations encode parameters as a NULL element and others omit them entirely. The correct encoding is to omit the parameters field; however, implementations MUST also handle a SHA AlgorithmIdentifier parameters field which contains a NULL. The AlgorithmIdentifier parameters field is OPTIONAL. If present, the parameters field MUST contain a NULL. Implementations MUST accept SHA2 AlgorithmIdentifiers with absent parameters. Implementations MUST accept SHA2 AlgorithmIdentifiers with NULL parameters. Implementations SHOULD generate SHA2 AlgorithmIdentifiers with absent parameters. Turner Expires January 25, 2008 [Page 3] Internet-Draft Using SHA2 Algorithms with CMS July 2007 2.1. SHA-224 The SHA-224 message digest algorithm is defined in [RFC3874]. The algorithm identifier for SHA-224 is: id-sha224 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 4 } The parameters are as specified in Section 2. 2.2. SHA-256 The SHA-256 message digest algorithm is defined in [SHA2]. The algorithm identifier for SHA-256 is: id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 1 } The parameters are as specified in Section 2. 2.3. SHA-384 The SHA-384 message digest algorithm is defined in [SHA2]. The algorithm identifier for SHA-384 is: id-sha384 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 2 } The parameters are as specified in Section 2. 2.4. SHA-512 The SHA-256 message digest algorithm is defined in [SHA2]. The algorithm identifier for SHA-512 is: id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistalgorithm(4) hashalgs(2) 3 } The parameters are as specified in Section 2. Turner Expires January 25, 2008 [Page 4] Internet-Draft Using SHA2 Algorithms with CMS July 2007 3. Signature Algorithms This section specifies the conventions employed by CMS implementations that support DSA [FIPS 186-3], ECDSA [X9.62], and RSA [RFC2313] with SHA2 algorithms. Signature algorithm identifiers are located in the SignerInfo signatureAlgorithm field of SignedData. Also, signature algorithm identifiers are located in the SignerInfo signatureAlgorithm field of countersignature attributes. Signature values are located in the SignerInfo signature field of SignedData. Also, signature values are located in the SignerInfo signature field of countersignature attributes. 3.1. DSA [RFC3370] section 3.1 specifies the conventions for DSA with SHA1 public key algorithm identifiers, parameters, public keys, and signature values. DSA with SHA2 algorithms use the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values. DSA MAY be used with SHA-224 and SHA-256. The algorithm identifier for DSA with SHA-224 signature values is: id-dsa-with-sha224 OBJECT IDENTIFIER ::= { joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) csor(3) algorithms(4) id-dsa-with-sha2(3) 1 } The algorithm identifier for DSA with SHA-224 signature values is: id-dsa-with-sha256 OBJECT IDENTIFIER ::= { joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) csor(3) algorithms(4) id-dsa-with-sha2(3) 2 } When either of these algorithm identifiers are used, the AlgorithmIdentifier parameters field MUST be absent. Turner Expires January 25, 2008 [Page 5] Internet-Draft Using SHA2 Algorithms with CMS July 2007 3.2. RSA [RFC3370] section 3.2 specifies the conventions for RSA with SHA-1 (PKCS #1 v1.5) public key algorithm identifiers, parameters, public keys, and signature values. RSA with SHA2 algorithms use the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values. RSA (PKCS #1 v1.5) MAY be used with SHA-224, SHA-256, SHA-384, or SHA-512. The object identifier for RSA with SHA-224 signature values is: sha224WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 14 } The object identifier for RSA with SHA-256 signature values is: sha256WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 11 } The object identifier for RSA with SHA-384 signature values is: sha384WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 12 } The object identifier for RSA with SHA-512 signature values is: sha512WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 13 } When any of these four object identifiers appears within an AlgorithmIdentifier, the parameters MUST be NULL. Implementations MUST accept the parameters being absent as well as present. 3.3. ECDSA [RFC3278] section 2.1 specifies the conventions for ECDSA with SHA1 public key algorithm identifiers, parameters, public keys, and signature values. ECDSA with SHA2 algorithms use the same conventions for these public key algorithm identifiers, parameters, public keys, and signature values, except that the digestAlgorithm MUST include the corresponding message digest algorithm identifier not sha-1 object identifier. ECDSA MAY be used with SHA-224, SHA-256, SHA-384, or SHA-512. Turner Expires January 25, 2008 [Page 6] Internet-Draft Using SHA2 Algorithms with CMS July 2007 The algorithm identifier for ECDSA with SHA-224 signature values is: ecdsa-with-SHA224 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 1 } The algorithm identifier for ECDSA with SHA-256 signature values is: ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 } The algorithm identifier for ECDSA with SHA-384 signature values is: ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 } The algorithm identifier for ECDSA with SHA-512 signature values is: ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 } When any of these four object identifiers appears within an AlgorithmIdentifier, the parameters MUST be NULL. 4. Security Considerations The security considerations in [RFC3278], [RFC3370], [RFC3874], [RFC4055], and [ECCADD] apply. No new security considerations are introduced as a result of this specification. 5. IANA Considerations None: All identifiers are already registered. Please remove this section prior to publication as an RFC. 6. References 6.1. Normative References [ECCADD] Dang, S., Santesson, S., Moriarty, K., and Brown, "Internet X.509 Public Key Infrastructure: Additional Algorithms and Identifiers for DSA and ECDSA", work-in- progress. [FIPS186-3] Federal Information Processing Standards Publication (FIPS PUB) 180-3, Secure Hash Standard (SHS), July 2007. Turner Expires January 25, 2008 [Page 7] Internet-Draft Using SHA2 Algorithms with CMS July 2007 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119. March 1997. [RFC2313] Kaliski, B., "PKCS #1: RSA Encryption Version 1.5", RFC 2313, March 1998. [RFC3278] Blake-Wilson, S., Brown, D., and P. Lambert, "Use of Elliptic Curve Cryptography (ECC) Algorithms in Cryptographic Message Syntax (CMS)", RFC 3278, April 2002. [RFC3370] Housley, R., "Cryptographic Message Syntax (CMS) Algorithms", RFC 3370, August 2002. [RFC3852] Housley, R., "The Cryptographic Message Syntax (CMS)", RFC 3852. July 2004. Housley, R., "Cryptographic Message Syntax (CMS) Multiple Signer Clarification", RFC 4852, April 2007. [RFC3874] Housley, R., "A 224-bit One Way Hash Function: SHA-224", RFC 3874. September 2004. [RFC4055] Schaad, J., Kaliski, B., and R. Housley, "Additional Algorithms and Identifiers for RSA Cryptography for use in the Internet Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 4055. June 2005. [SHA2] National Institute of Standards and Technology (NIST), FIPS Publication 180-2: Secure Hash Standard, 1 August 2002. [X9.62] X9.62-2005, "Public Key Cryptography for the Financial Services Industry: The Elliptic Curve Digital Signature Standard (ECDSA)", November, 2005. 6.2. Informative References [RFC4231] Nystrom, A. "Identifiers and Test Vectors for HMAC-SHA- 224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512", RFC4231. December 2005. Turner Expires January 25, 2008 [Page 8] Internet-Draft Using SHA2 Algorithms with CMS July 2007 Author's Addresses Sean Turner IECA, Inc. Email: turners@ieca.com Turner Expires January 25, 2008 [Page 9] Internet-Draft Using SHA2 Algorithms with CMS July 2007 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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