Secure Inter-Domain Routing (sidr) M. Lepinski
Internet Draft S. Kent
Expires: August 16, 2011 D. Kong
Intended Status: Proposed Standard BBN Technologies
February 16, 2011
A Profile for Route Origin Authorizations (ROAs)
draft-ietf-sidr-roa-format-10.txt
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Abstract
This document defines a standard profile for Route Origin
Authorizations (ROAs). A ROA is a digitally signed object that
provides a means of verifying that an IP address block holder has
authorized an Autonomous System (AS) to originate routes to that one
or more prefixes within the address block.
Table of Contents
1. Introduction...................................................2
1.1. Terminology...............................................3
2. The ROA ContentType............................................3
3. The ROA eContent...............................................3
3.1. version...................................................4
3.2. asID......................................................4
3.3. ipAddrBlocks..............................................4
4. ROA Validation.................................................5
5. Security Considerations........................................5
6. IANA Considerations............................................6
7. Acknowledgments................................................6
8. References.....................................................7
8.1. Normative References......................................7
8.2. Informative References....................................7
APPENDIX A: ASN.1 Module..........................................8
Authors' Addresses................................................9
1. Introduction
The primary purpose of the Internet IP Address and Autonomous System
(AS) Number Resource Public Key Infrastructure (RPKI) system is to
improve routing security. (See [ARCH] for more information.) As part
of this system, a mechanism is needed to allow entities to verify
that an AS has been given permission by an IP address block holder to
advertise routes to one or more prefixes within that block. A ROA
provides this function.
The ROA makes use of the template for RPKI digitally signed objects
[SIGNOBJ], which defines a Crytopgraphic Message Syntax (CMS)
[RFC5652] wrapper for the ROA content as well as a generic validation
procedure for RPKI signed objects. Therefore, to complete the
specification of the ROA (see Section 4 of [SIGNOBJ]), this document
defines:
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1. The OID that identifies the signed object as being a ROA. (This
OID appears within the eContentType in the encapContentInfo
object as well as the ContentType signed attribute in the
signerInfo object.)
2. The ASN.1 syntax for the ROA eContent. (This is the payload
that specifies the AS being authorized to originate routes as
well as the prefixes to which the AS may originate routes.)
3. An additional step required to validate ROAs (in addition to
the validation steps specified in [SIGNOBJ]).
1.1. Terminology
It is assumed that the reader is familiar with the terms and concepts
described in "Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile" [RFC5280] and "X.509
Extensions for IP Addresses and AS Identifiers" [RFC3779].
Additionally, this document makes use of the RPKI signed object
profile [SIGNOBJ] and thus familiarity with that document is assumed.
Note that the RPKI signed object profile makes use of certificates
adhering to the RPKI resource certificate profile [RESCERT] and thus
familiarly with this profile is also assumed.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC-2119 [RFC2119].
2. The ROA ContentType
The ContentType for a ROA is defined as routeOriginAuthz and has the
numerical value of 1.2.840.113549.1.9.16.1.24.
This OID MUST appear both within the eContentType in the
encapContentInfo object as well as the ContentType signed attribute
in the signerInfo object (see [SIGNOBJ]).
3. The ROA eContent
The content of a ROA identifies a single AS that has been authorized
by the address space holder to originate routes and a list of one or
more IP address prefixes that will be advertised. If the address
space holder needs to authorize multiple ASes to advertise the same
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set of address prefixes, the holder issues multiple ROAs, one per AS
number. A ROA is formally defined as:
RouteOriginAttestation ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
asID ASID,
ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily }
ASID ::= INTEGER
ROAIPAddressFamily ::= SEQUENCE {
addressFamily OCTET STRING (SIZE (2..3)),
addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress }
ROAIPAddress ::= SEQUENCE {
address IPAddress,
maxLength INTEGER OPTIONAL }
IPAddress ::= BIT STRING
Note that this content appears as the eContent within the
encapContentInfo (see [SIGNOBJ]).
3.1. version
The version number of the RouteOriginAttestation MUST be 0.
3.2. asID
The asID field contains the AS number that is authorized to originate
routes to the given IP address prefixes.
3.3. ipAddrBlocks
The ipAddrBlocks field encodes the set of IP address prefixes to
which the AS is authorized to originate routes. Note that the syntax
here is more restrictive than that used in the IP Address Delegation
extension defined in RFC 3779. That extension can represent arbitrary
address ranges, whereas ROAs need to represent only prefixes.
Within the ROAIPAddressFamily structure, addressFamily contains the
Address Family Identifier (AFI) of an IP address family. This
specification only supports IPv4 and IPv6. Therefore, addressFamily
MUST be either 0001 or 0002.
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Within a ROAIPAddress structure, the addresses field represents
prefixes as a sequence of type IPAddress. (See [RFC3779] for more
details). If present, the maxLength MUST be an integer greater than
or equal to the length of the accompanying prefix and less than or
equal to the length (in bits) of an IP address in the address family
(32 for IPv4 and 128 for IPv6). When present, the maxLength specifies
the maximum length of IP address prefix that the AS is authorized to
advertise. (For example, if the IP Address prefix is 203.0.113/24 and
the maxLength is 26, the AS is authorized to advertise any more
specific prefix having length at most 26. That is, in this example,
the AS would be authorized to advertise 203.0.113/24,
203.0.113.128/25, or 203.0.113.0/25, but not 203.0.113.0/27.) When
the maxLength is not present, the AS is only authorized to advertise
exactly the prefix specified in the ROA.
Note that a valid ROA may contain an IP Address prefix (within a
ROAIPAddress element) that is encompassed by another IP Address
prefix (within a separate ROAIPAddress element). For example, a ROA
may contain the prefix 203.0.113/24 with maxLength 26, as well as the
prefix 203.0.113.0/28 with maxLength 28. (Such a ROA would authorize
the indicated AS to advertise any prefix beginning with 203.0.113
with length at least 24 and no greater than 26, as well as the
specific prefix 203.0.113.0/28.) Additionally, a ROA MAY contain two
ROAIPAddress elements where the IP Address prefix is identical in
both cases. However, this is NOT RECOMMENDED as in such a case the
ROAIPAddress with the shorter maxLength grants no additional
privileges to the indicated AS and thus can be omitted without
changing the meaning of the ROA.
4. ROA Validation
Before a relying party can use a ROA to validate a routing
announcement, the relying party MUST first validate the ROA. To
validate a ROA the relying party MUST perform all the validation
checks specified in [SIGNOBJ] as well as the following additional
ROA-specific validation step.
1. The IP Address Delegation extension [RFC3779] is present in the
End-Entity (EE) certificate (contained within the ROA) and each IP
address prefix(es) in ROA is contained within the set of IP
addresses specified by the EE certificate's IP address delegation
extension.
5. Security Considerations
There is no assumption of confidentiality for the data in a ROA; it
is anticipated that ROAs will be stored in repositories that are
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accessible to all ISPs, and perhaps to all Internet users. There is
no explicit authentication associated with a ROA, since the PKI used
for ROA validation provides authorization but not authentication.
Although the ROA is a signed, application layer object, there is no
intent to convey non-repudiation via a ROA.
The purpose of a ROA is to convey authorization for an AS to
originate a route to the prefix(es) in the ROA. Thus the integrity of
a ROA MUST be established. The ROA specification makes use of the
RPKI signed object format, thus all security considerations in
[SIGNOBJ] also apply to ROAs. Additionally, the signed object profile
uses the CMS signed message format for integrity, and thus ROA
inherit all security considerations associated with that data
structure.
The right of the ROA signer to authorize the target AS to originate
routes to the prefix(es) is established through use of the address
space and AS number PKI described in [ARCH]. Specifically one MUST
verify the signature on the ROA using an X.509 certificate issued
under this PKI, and check that the prefix(es) in the ROA match those
in the address space extension in the certificate.
6. IANA Considerations
None.
7. Acknowledgments
The authors wish to thank Charles Gardiner and Russ Housley for their
help and contributions. Additionally, the authors would like to thank
Rob Austein, Roque Gagliano, Danny McPherson and Sam Weiler for their
careful reviews and helpful comments.
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5652] Housley, R., "Cryptographic Message Syntax", RFC 5652,
September 2009.
[RFC3779] Lynn, C., Kent, S., and Seo, K., "X.509 Extensions for IP
Addresses and AS Identifiers", RFC 3779, June 2004.
[RFC5280] Cooper, D., et. al., "Internet X.509 Public Key
Infrastructure and Certificate Revocation List (CRL)
Profile", RFC 5280, May 2008.
[RESCERT] Huston, G., Michaelson, G., and Loomans, R., "A Profile for
X.509 PKIX Resource Certificates", draft-ietf-sidr-res-
certs, November 2010.
[SIGNOBJ] Lepinski, M., Chi, A., and Kent, S., "Generic Signed
Objects for the Resource Public Key Infrastructure", draft-
ietf-sidr-signed-object, February 2011.
8.2. Informative References
[ARCH] Lepinski, M. and Kent, S., "An Infrastructure to Support
Secure Internet Routing," draft-ietf-sidr-arch, February
2011.
[REPOS] Huston, G., Michaelson, G., and Loomans, R., "A Profile for
Resource Certificate Repository Structure", draft-ietf-
sidr-repos-struct, November 2010.
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APPENDIX A: ASN.1 Module
This normative appendix provides an ASN.1 module that specifies the
ROA content in ASN.1 syntax.
id-mod-rpkiROA { iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs9(9) smime(16) mod(0) 61 }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
RouteOriginAttestation ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
asID ASID,
ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily }
ASID ::= INTEGER
ROAIPAddressFamily ::= SEQUENCE {
addressFamily OCTET STRING (SIZE (2..3)),
addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress }
ROAIPAddress ::= SEQUENCE {
address IPAddress,
maxLength INTEGER OPTIONAL }
IPAddress ::= BIT STRING
END
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Authors' Addresses
Matt Lepinski
BBN Technologies
10 Moulton Street
Cambridge MA 02138
Email: mlepinski@bbn.com
Stephen Kent
BBN Technologies
10 Moulton Street
Cambridge MA 02138
Email: skent@bbn.com
Derrick Kong
BBN Technologies
10 Moulton Street
Cambridge MA 02138
Email: dkong@bbn.com
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