Secure Inter-Domain Routing (sidr) M. Lepinski Internet Draft S. Kent Expires: April 26, 2010 D. Kong Intended Status: Proposed Standard BBN Technologies October 26, 2009 A Profile for Route Origin Authorizations (ROAs) draft-ietf-sidr-roa-format-06.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 April 26, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. 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 Lepinski, Kent and Kong Expires April 2010 [Page 1] Internet-Draft Route Origin Authorizations October 2009 authorized an Autonomous System (AS) to originate routes to that one or more prefixes within the address block. Table of Contents 1. Introduction...................................................2 2. Basic Format...................................................3 2.1. Signed-Data Content Type..................................4 2.1.1. version..............................................4 2.1.2. digestAlgorithms.....................................4 2.1.3. encapContentInfo.....................................4 2.1.3.1. eContentType....................................4 2.1.3.2. eContent........................................5 2.1.3.2.1. version....................................5 2.1.3.2.2. asID.......................................5 2.1.3.2.3. ipAddrBlocks...............................5 2.1.4. certificates.........................................6 2.1.5. crls.................................................6 2.1.6. signerInfos..........................................7 2.1.6.1. version.........................................7 2.1.6.2. sid.............................................7 2.1.6.3. digestAlgorithm.................................7 2.1.6.4. signedAttrs.....................................7 2.1.6.4.1. ContentType Attribute......................8 2.1.6.4.2. MessageDigest Attribute....................8 2.1.6.4.3. SigningTime Attribute......................8 2.1.6.4.4. BinarySigningTimeAttribute.................9 2.1.6.5. signatureAlgorithm..............................9 2.1.6.6. signature......................................10 2.1.6.7. unsignedAttrs..................................10 3. ROA Validation................................................10 4. Security Considerations.......................................11 5. IANA Considerations...........................................12 6. Acknowledgments...............................................12 7. References....................................................13 7.1. Normative References.....................................13 7.2. Informative References...................................13 Authors' Addresses...............................................14 Intellectual Property Statement..................................14 Disclaimer of Validity...........................................14 Copyright Statement..............................................14 1. Introduction The primary purpose of the Internet IP Address and AS Number Resource Public Key Infrastructure (RPKI) system is to improve routing Lepinski, Kent and Kong Expires April 2010 [Page 2] Internet-Draft Route Origin Authorizations October 2009 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. 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. 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]. 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]. 1.2. Note on Algorithms Cryptographic Message Syntax is a general format capable of accommodating a wide variety of signature and digest algorithms. This specification takes no stand with regards to the signature and digest algorithms that are appropriate for use in a ROA. Appropriate algorithms and associated key sizes are specified in a separate document [ALGS]. 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] Lepinski, Kent and Kong Expires April 2010 [Page 3] Internet-Draft Route Origin Authorizations October 2009 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 Additionally, the SignerInfos set must contain only a single SignerInfo object. 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 contains the OIDs of the digest algorithm(s) used in signing the encapsulated content. This set MUST conform to the RPKI Algorithms and Key Size Profile specification [ALGS]. 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. Lepinski, Kent and Kong Expires April 2010 [Page 4] Internet-Draft Route Origin Authorizations October 2009 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, ipAddrBlocks SEQUENCE OF ROAIPAddressFamily } ASID ::= INTEGER ROAIPAddressFamily ::= SEQUENCE { addressFamily OCTET STRING (SIZE (2..3)), addresses SEQUENCE OF ROAIPAddress } ROAIPAddress ::= SEQUENCE { address IPAddress, maxLength INTEGER OPTIONAL } IPAddress ::= BIT STRING 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. ipAddrBlocks The ipAddrBlocks field encodes the set of IP address prefixes to which the AS is authorized to originate routes. Note that the syntax Lepinski, Kent and Kong Expires April 2010 [Page 5] Internet-Draft Route Origin Authorizations October 2009 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. 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 10.0/16 and the maxLength is 24, the AS is authorized to advertise any more specific prefix having length at most 24. That is, in this example, the AS would be authorized to advertise 10.0/16, 10.0.128/20, or 10.0.255/24, but not 10.0.255.0/25.) 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 10.0/16 with maxLength 18, as well as the prefix 10.0.0/24 with maxLength 24. (Such a ROA would authorize the indicated AS to advertise any prefix beginning with 10.0 with length at least 16 and no greater than 18, as well as the specific prefix 10.0.0/24.) 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. 2.1.4. certificates The certificates field MUST be included and MUST contain only the end entity certificate needed to validate this ROA. 2.1.5. crls The crls field MUST be omitted. Lepinski, Kent and Kong Expires April 2010 [Page 6] Internet-Draft Route Origin Authorizations October 2009 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 consist of the OID of a digest algorithm that conforms to the RPKI Algorithms and Key Size Profile specification [ALGS]. 2.1.6.4. signedAttrs The signedAttrs is defined as: SignedAttributes ::= SET SIZE (1..MAX) OF Attribute Attribute ::= SEQUENCE { attrType OBJECT IDENTIFIER, attrValues SET OF AttributeValue } AttributeValue ::= ANY Lepinski, Kent and Kong Expires April 2010 [Page 7] Internet-Draft Route Origin Authorizations October 2009 The signedAttr element MUST be present and MUST include the content- type and message-digest attributes. The signer MAY also include the signing-time signed attribute, the binary-signing-time signed attribute, or both signed attributes. Other signed attributes that are deemed appropriate MAY also be included. The intent is to allow additional signed attributes to be included if a future need is identified. This does not cause an interoperability concern because unrecognized signed attributes are ignored by the relying party. The signedAttr MUST include only a single instance of any particular attribute. Additionally, even though the syntax allows for a SET OF AttributeValue, in a ROA the attrValues must consist of only a single AttributeValue. 2.1.6.4.1. ContentType Attribute The ContentType attribute MUST be present. The attrType OID for the ContentType attribute is 1.2.840.113549.1.9.3. The attrValues for the ContentType attribute in a ROA MUST be 1.2.840.113549.1.9.16.1.24 (matching the eContentType in the EncapsulatedContentInfo). 2.1.6.4.2. MessageDigest Attribute The MessageDigest Attribute MUST be present. The attrType OID for the MessageDigest Attribute is 1.2.840.113549.1.9.4. The attrValues for the MessageDigest attribute contains the output of the digest algorithm applied to the content being signed, as specified in Section 11.1 of RFC 3852. 2.1.6.4.3. SigningTime Attribute The SigningTime Attribute MAY be present. If it is present it MUST be ignored by the relying party. The presence of absence of the SigningTime attribute in no way affects the validation of the ROA (as specified in Section 3). The attrType OID for the SigningTime attribute is 1.2.840.113549.1.9.5. The attrValues for the SigningTime attribute is defined as: Lepinski, Kent and Kong Expires April 2010 [Page 8] Internet-Draft Route Origin Authorizations October 2009 SigningTime ::= Time Time ::= CHOICE { utcTime UTCTime, generalizedTime GeneralizedTime } The Time element specifies the time, based on the local system clock, at which the digital signature was applied to the content. The definition of Time matches the one specified in the 1997 version of X.509. Additional information regarding the use of UTCTime and GeneralizedTime can we found in [RFC3852]. 2.1.6.4.4. BinarySigningTimeAttribute The BinarySigningTime Attribute MAY be present. If it is present it MUST be ignored by the relying party. The presence of absence of the BinarySigningTime attribute in no way affects the validation of the ROA (as specified in Section 3). The attrType OID for the SigningTime attribute is 1.2.840.113549.1.9.16.2.46. The attrValues for the SigningTime attribute is defined as: BinarySigningTime ::= BinaryTime BinaryTime ::= INTEGER (0..MAX) The BinaryTime element specifies the time, based on the local system clock, at which the digital signature was applied to the content. The precise definition of the BinaryTime element can be found in [RFC4049]. 2.1.6.5. signatureAlgorithm The signatureAlgorithm MUST consist of the OID of a signature algorithm that conforms RPKI Algorithms and Key Size Profile specification [ALGS]. Lepinski, Kent and Kong Expires April 2010 [Page 9] Internet-Draft Route Origin Authorizations October 2009 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 validate the ROA by verifying that all of the following conditions hold. (Note that a relying party may perform these checks in any order.) 1. The ROA syntax complies with this specification. In particular, that each of the following is true: 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 certificates field in the SignedData object is present and contains an EE certificate whose Subject Key Identifier (SKI) matches the sid field of the SignerInfo object. 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. Lepinski, Kent and Kong Expires April 2010 [Page 10] Internet-Draft Route Origin Authorizations October 2009 i. The signedAttrs field in the SignerInfo object is present and contains both the ContentType attribute (OID 1.2.840.113549.1.9.3) and the MessageDigest attribute (OID 1.2.840.113549.1.9.4). j. The unsignedAttrs field in the SignerInfo object is omitted. k. The digestAlgorithm in the SignedData and SignerInfo objects as well as the signatureAlgorithm in the SignerInfo object conform to the RPKI Algorithms and Key Size Profile specification [ALGS]. 2. The public key of the end-entity certificate (contained within the ROA) can be used to successfully verify the signature on the ROA. 3. The IP Address Delegation extension [RFC3779] is present in the 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. 4. The EE certificate (contained within the ROA) is a valid end- entity certificate in the resource PKI as specified by [RESCERT]. (In particular, there exists a valid certification path from a trust anchor to the EE certificate.) 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 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. Lepinski, Kent and Kong Expires April 2010 [Page 11] Internet-Draft Route Origin Authorizations October 2009 5. IANA Considerations None. 6. Acknowledgments The authors wish to thank Charles Gardiner and Russ Housley for their help and contributions. Additionally, the authors would like to thank Danny McPherson and Roque Gagliano for their careful reviews and helpful comments. Lepinski, Kent and Kong Expires April 2010 [Page 12] Internet-Draft Route Origin Authorizations October 2009 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. [RFC3779] Lynn, C., Kent, S., and Seo, K., "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, June 2004. [ALGS] Huston, G., "A Profile for Algorithms and Key Sizes for use in the Resource Public Key Infrastructure", draft-ietf- sidr-rpki-algs-00, August 2009 7.2. Informative References [ARCH] Lepinski, M. and Kent, S., "An Infrastructure to Support Secure Internet Routing," draft-ietf-sidr-arch-09, October 2009. [CP] Seo, K., et. al., "A Certificate Policy for the Resource PKI," draft-ietf-sidr-cp-07, October 2009. [RESCERT] Huston, G., Michaelson, G., and Loomans, R., "A Profile for X.509 PKIX Resource Certificates," draft-ietf-sidr-res- certs-17, August 2009. [RFC4049] Housley, R., "BinaryTime: An Alternative Format for Representing Time in ASN.1," RFC 4049, April 2005. Lepinski, Kent and Kong Expires April 2010 [Page 13] Internet-Draft Route Origin Authorizations October 2009 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 Pre-5378 Material Disclaimer This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Lepinski, Kent and Kong Expires April 2010 [Page 14]