Secure Inter-Domain Routing (sidr) M. Lepinski Internet Draft S. Kent Expires: August 2008 D. Kong Intended Status: Proposed Standard BBN Technologies February 25, 2008 A Profile for Route Origin Authorizations (ROAs) draft-ietf-sidr-roa-format-02.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 8, 2008. 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. 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 RFC-2119 [RFC2119]. Lepinski, Kent and Kong Expires August 2008 [Page 1] Internet-Draft Route Origin Attestation Profile February 2008 Table of Contents 1. Introduction...................................................2 2. Basic Format...................................................3 2.1. Signed-Data Content Type..................................3 2.1.1. version..............................................3 2.1.2. digestAlgorithms.....................................3 2.1.3. encapContentInfo.....................................4 2.1.3.1. eContentType....................................4 2.1.3.2. eContent........................................4 2.1.3.2.1. version....................................5 2.1.3.2.2. asID.......................................5 2.1.3.2.3. requireExactMatch..........................5 2.1.3.2.4. ipAddrBlocks...............................5 2.1.4. certificates.........................................5 2.1.5. crls.................................................5 2.1.6. signerInfos..........................................6 2.1.6.1. version.........................................6 2.1.6.2. sid.............................................6 2.1.6.3. digestAlgorithm.................................6 2.1.6.4. signedAttrs.....................................6 2.1.6.5. signatureAlgorithm..............................6 2.1.6.6. signature.......................................7 2.1.6.7. unsignedAttrs...................................7 3. ROA Validation.................................................7 4. Security Considerations........................................8 5. IANA Considerations............................................9 6. Acknowledgments................................................9 7. References....................................................10 7.1. Normative References.....................................10 7.2. Informative References...................................10 Author's Addresses...............................................11 Intellectual Property Statement..................................12 Disclaimer of Validity...........................................12 Copyright Statement..............................................12 1. Introduction The primary purpose of the Internet IP Address and AS Number Resource Public Key Infrastructure (RPKI) system is to improve routing security. 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. Lepinski, Kent and Kong Expires August 2008 [Page 2] Internet-Draft Route Origin Attestation Profile February 2008 A ROA is a digitally signed object that makes use of Cryptographic Message Syntax (CMS) [RFC3852] as a standard encapsulation format. CMS was chosen to take advantage of existing open source software available for processing messages in this format. 2. Basic Format Using CMS syntax, a ROA is a type of signed-data object. The general format of a CMS object is: ContentInfo ::= SEQUENCE { contentType ContentType, content [0] EXPLICIT ANY DEFINED BY contentType } ContentType ::= OBJECT IDENTIFIER As a ROA is a signed-data object, it uses the corresponding OID, 1.2.840.113549.1.7.2. [RFC3852] 2.1. Signed-Data Content Type According to the CMS standard, the signed-data content type shall have ASN.1 type SignedData: SignedData ::= SEQUENCE { version CMSVersion, digestAlgorithms DigestAlgorithmIdentifiers, encapContentInfo EncapsulatedContentInfo, certificates [0] IMPLICIT CertificateSet OPTIONAL, crls [1] IMPLICIT RevocationInfoChoices OPTIONAL, signerInfos SignerInfos } DigestAlgorithmIdentifiers ::= SET OF DigestAlgorithmIdentifier SignerInfos ::= SET OF SignerInfo 2.1.1. version The version is the syntax version number. It MUST be 3, corresponding to the signerInfo structure having version number 3. 2.1.2. digestAlgorithms The digestAlgorithms set MUST include only SHA-256, the OID for which is 2.16.840.1.101.3.4.2.1. [RFC4055] It MUST NOT contain any other algorithms. Lepinski, Kent and Kong Expires August 2008 [Page 3] Internet-Draft Route Origin Attestation Profile February 2008 2.1.3. encapContentInfo encapContentInfo is the signed content, consisting of a content type identifier and the content itself. EncapsulatedContentInfo ::= SEQUENCE { eContentType ContentType, eContent [0] EXPLICIT OCTET STRING OPTIONAL } ContentType ::= OBJECT IDENTIFIER 2.1.3.1. eContentType The ContentType for a ROA is defined as routeOriginAttestation and has the numerical value of 1.2.840.113549.1.9.16.1.24. id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) 16 } id-ct OBJECT INDENTIFIER ::= { id-smime 1 } routeOriginAttestion OBJECT IDENTIFIER ::= { id-ct 24 } 2.1.3.2. 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 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, exactMatch BOOLEAN ipAddrBlocks ROAIPAddrBlocks } ASID ::= INTEGER ROAIPAddrBlocks ::= SEQUENCE of ROAIPAddressFamily ROAIPAddressFamily ::= SEQUENCE { addressFamily OCTET STRING (SIZE (2..3)), addresses SEQUENCE OF IPAddress } IPAddress ::= BIT STRING Lepinski, Kent and Kong Expires August 2008 [Page 4] Internet-Draft Route Origin Attestation Profile February 2008 2.1.3.2.1. version The version number of the RouteOriginAttestation MUST be 0. 2.1.3.2.2. asID The asID field contains the AS number that is authorized to originate routes to the given IP address prefixes. 2.1.3.2.3. requireExactMatch A value of TRUE in the requireExactMatch field indicates that the AS is authorized to originate routes only for the prefix(es) specified in the ROA, not for any more specific prefix(es). A value of FALSE in the requireExactMatch field indicates that the AS is authorized to originate routes not only for prefix(es) listed in the ROA, but also for any more specific (longer) prefix(es). 2.1.3.2.4. 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. The addresses field represents prefixes as a sequence of type IPAddress. (See [RFC3779] for more details). 2.1.4. certificates The certificates field MAY be included. If so, it MUST contain only the end entity certificate needed to validate this ROA. This certificate should be present only if the ROA is being transmitted to a relying party. Thus in the initial use of ROAs, where they are being made available to relying parties via a repository system, this certificate SHOULD be omitted. 2.1.5. crls The crls field MUST be omitted. Lepinski, Kent and Kong Expires August 2008 [Page 5] Internet-Draft Route Origin Attestation Profile February 2008 2.1.6. signerInfos SignerInfo is defined under CMS as: SignerInfo ::= SEQUENCE { version CMSVersion, sid SignerIdentifier, digestAlgorithm DigestAlgorithmIdentifier, signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL, signatureAlgorithm SignatureAlgorithmIdentifier, signature SignatureValue, unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL } 2.1.6.1. version The version number MUST be 3, corresponding with the choice of SubjectKeyIdentifier for the sid. 2.1.6.2. sid The sid is defined as: SignerIdentifier ::= CHOICE { issuerAndSerialNumber IssuerAndSerialNumber, subjectKeyIdentifier [0] SubjectKeyIdentifier } For a ROA, the sid MUST be a SubjectKeyIdentifier. 2.1.6.3. digestAlgorithm The digestAlgorithm MUST be SHA-256, the OID for which is 2.16.840.1.101.3.4.2.1. [RFC4055] 2.1.6.4. signedAttrs signedAttrs MUST be omitted. 2.1.6.5. signatureAlgorithm The signatureAlgorithm MUST be RSA (rsaEncryption), the OID for which is 1.2.840.113549.1.1.1. Lepinski, Kent and Kong Expires August 2008 [Page 6] Internet-Draft Route Origin Attestation Profile February 2008 2.1.6.6. signature The signature value is defined as: SignatureValue ::= OCTET STRING The signature characteristics are defined by the digest and signature algorithms. 2.1.6.7. unsignedAttrs unsignedAttrs MUST be omitted. 3. ROA Validation Before a relying party can use a ROA to validate a routing announcement, the relying party must first use the resource PKI to validate the ROA by performing the following steps. 1. Verify that the ROA syntax complies with this specification. In particular, verify the following: a. The contentType of the CMS object is SignedData (OID 1.2.840.113549.1.7.2) b. The version of the SignedData object is 3. c. The digestAlgorithm in the SignedData object is SHA-256 (OID 2.16.840.1.101.3.4.2.1). d. The crls field in the SignedData object is omitted. e. The eContentType in the EncapsulatedContentInfo is routeOriginAttestation (OID 1.2.840.113549.1.9.16.1.24) f. The version of the RouteOriginAttestation is 0. g. The addressFamily in the ROAIPAddressFamily is either IPv4 or IPv6 (0001 and 0002, respectively). h. The version of the SignerInfo is 3. i. The digestAlgorithm in the SignerInfo object is SHA-256 (OID 2.16.840.1.101.3.4.2.1). j. The signatureAlgorithm in the SignerInfo object is RSA (OID 1.2.840.113549.1.1.1). Lepinski, Kent and Kong Expires August 2008 [Page 7] Internet-Draft Route Origin Attestation Profile February 2008 k. The signedAttrs field in the SignerInfo object is omitted. l. The unsignedAttrs field in the SignerInfo object is omitted. 2. Obtain an EE certificate whose Subject Key Identifier (SKI) matches the sid field of the SignerInfo object. This certificate may be obtained from the certificates field of the SignedData object (if present), the resource PKI repository system, or a local cache. 3. Use the public key in the EE certificate to verify the signature on the ROA. 4. Verify that the EE certificate has an IP Address Delegation extension [RFC3779] and that the IP address prefix(es) in that extension exactly matches the IP address prefix(es) in the ROA. 5. Verify that the EE certificate is a valid end-entity certificate in the resource PKI by constructing a valid certificate path to a trust anchor. (See [RESCERT] for more details.) Note that requiring an exact match between the IP address prefix(es) in a ROA and the IP address prefix(es) in the corresponding EE certificate does not place any limitations on ROA use. Indeed, since each EE certificate in the resource RPKI architecture is used to verify only a single ROA, it is natural to have the IP address prefixes in the certificate match those in the corresponding ROA. When the issuer of a ROA does not require an exact match between the IP address prefix(es) in the ROA and the prefix(es) advertised by the AS (when it originates routes for the prefix), the issuer sets the exactMatch flag in the ROA to FALSE. 4. 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 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 makes use of the CMS signed message format for integrity, and thus inherits the security considerations associated with that data structure. The right of the Lepinski, Kent and Kong Expires August 2008 [Page 8] Internet-Draft Route Origin Attestation Profile February 2008 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. 5. IANA Considerations None. 6. Acknowledgments The authors wish to thank Charles Gardiner and Russ Housley for their help and contributions. Lepinski, Kent and Kong Expires August 2008 [Page 9] Internet-Draft Route Origin Attestation Profile February 2008 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3852] Housley, R., "Cryptographic Message Syntax", RFC 3852, July 2004. [RFC4055] Schaad, J., Kaliski, B., and Housley, R., "Additional Algorithms and Identifiers for RSA Cryptography for use in the Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 4055, June 2005. [RFC3779] Lynn, C., Kent, S., and Seo, K., "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, June 2004. 7.2. Informative References [RSA] Rivest, R., Shamir, A., and Adelman, L. M. 1978. A method for obtaining digital signatures and public-key cryptosystems. Commun. ACM 21, 2 (Feb.), 120-126. [ARCH] Lepinski, M., Kent, S., and Barnes, R., "An Infrastructure to Support Secure Internet Routing," draft-ietf-sidr-arch- 03.txt, February, 2008 (work in progress). [RESCERT] Huston, G., Michaelson, G., and Loomans, R., "A Profile for X.509 PKIX Resource Certificates," draft-ietf-sidr-res- certs-09.txt, November, 2007 (work in progress). Lepinski, Kent and Kong Expires August 2008 [Page 10] Internet-Draft Route Origin Attestation Profile February 2008 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 Lepinski, Kent and Kong Expires August 2008 [Page 11] Internet-Draft Route Origin Attestation Profile February 2008 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. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Lepinski, Kent and Kong Expires August 2008 [Page 12]