Secure Inter-Domain Routing (SIDR) G. Huston Internet-Draft G. Michaelson Intended status: Standards Track APNIC Expires: May 2, 2009 T. Manderson October 29, 2008 A Profile for Bogon Origin Attestations (BOAs) draft-ietf-sidr-bogons-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 May 2, 2009. Abstract This document defines a standard profile for Bogon Origin Attestations (BOAs). A BOA is a digitally signed object that provides a means of verifying that an IP address block holder has not authorized any Autonomous System (AS) to originate routes that are equivalent to any of the addresses listed in the BOA. A BOA also provides a means of verifying that BGP speaker is not using an AS without appropriate authority to use that AS. The proposed application of BOAs is intended to fit within the requirements for adding security measures to inter-domain routing, including the ability to support incremental and piecemeal deployment of such measures, and does not require any changes to the specification of Huston, et al. Expires May 2, 2009 [Page 1] Internet-Draft Bogon Attestations October 2008 the Border Gateway Protocol. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 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 2.1.4. certificates . . . . . . . . . . . . . . . . . . . . . 6 2.1.5. crls . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.6. signerInfo . . . . . . . . . . . . . . . . . . . . . . 6 3. BOA Validation . . . . . . . . . . . . . . . . . . . . . . . . 9 4. BOA Use Practices . . . . . . . . . . . . . . . . . . . . . . 11 5. BOA Interpretation . . . . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 9. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . . . . 15 Huston, et al. Expires May 2, 2009 [Page 2] Internet-Draft Bogon Attestations October 2008 1. Introduction This document defines an application of the Resource Public Key Infrastructure (RPKI) to validate the attestations of Internet Registries that certain addresses are currently neither allocated nor assigned to any party, and any appearance of such addresses or AS's in a routing advertisement in the Border Gateway Protocol (BGP) [RFC4271] should be considered an invalid use of such addresses or AS's. The RPKI is based on Resource Certificates. Resource Certificates are X.509 certificates that conform to the PKIX profile [RFC5280], and to the extensions for IP addresses and AS identifiers [RFC3779]. A Resource Certificate describes an action by an Issuer that binds a list of IP address blocks and Autonomous System (AS) numbers to the Subject of a certificate, identified by the unique association of the Subject's private key with the public key contained in the Resource Certificate. The RPKI is structured such that each current Resource Certificate matches a current resource allocation or assignment. This is described in [ID.sidr-arch]. BOAs can be regarded as a logical opposite of a Route Origin Authorization (ROA) [ID.sidr-roa-format], and allows a resource holder to explicitly list those IP addresses and AS's that are denoted by the holder as not validly appearing in any routing advertisement, and to make this attestation in a manner that a relying party can validate under the framework of the RPKI. A BOA 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 BOA 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 Huston, et al. Expires May 2, 2009 [Page 3] Internet-Draft Bogon Attestations October 2008 2.1. Signed-Data Content Type According to the CMS specification, 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. 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 BOA is defined as id-ct-rpkiBOA, and has the numerical value of 1.2.840.113549.1.9.16.1.[TBD]. [This value needs to be assigned via an OID registration.] Huston, et al. Expires May 2, 2009 [Page 4] Internet-Draft Bogon Attestations October 2008 id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) 16 } id-ct OBJECT IDENTIFIER ::= { id-smime 1 } id-ct-rpkiBOA OBJECT IDENTIFIER ::= { id-ct [TBD] } 2.1.3.2. eContent The content of a BOA identifies a list of one or more AS's and one or more IP address prefixes that are asserted to be "bogons" and, accordingly, BOAs are intended to act as a constraint on the routing system to signal that no route object that that relates to these AS's or IP addresses should be interpreted as representing a valid routing attestation. A BOA is formally defined as: id-ct-rpkiBOA ::= { version [0] INTEGER DEFAULT 0, asIDs SEQUENCE OF asIdsOrRange, ipAddrBlocks SEQUENCE OF BOAIPAddressFamily } ASIdOrRange ::= CHOICE { id ASId, range ASRange } ASRange ::= SEQUENCE { min ASId, max ASId } ASId ::= INTEGER BOAIPAddressFamily ::= SEQUENCE { addressFamily OCTET STRING (SIZE (2..3)), addresses SEQUENCE OF IPAddress } IPAddress ::= BIT STRING 2.1.3.2.1. version The version number of the BogonOriginAttestation MUST be 0. 2.1.3.2.2. asIDs The asIDs field contains the AS numbers that are to be regarded as Bogon AS's. The set of AS numbers may be explicitly listed, or specified as a continuous range of values. The field is to be formatted as per the canonical format specified in [RFC3779]. Huston, et al. Expires May 2, 2009 [Page 5] Internet-Draft Bogon Attestations October 2008 2.1.3.2.3. BOAIPAddressFamily The BOAIPAddressFamily field encodes the set of IP address prefixes that are to be regarded as Bogon IP addresses that are to be constrained from appearing in any routing advertisement. The intended semantics of an address prefix in a BOA is that any route object that has the same address prefix as that listed as a Bogon IP address, or is a more specific prefix of a Bogon IP address can be regarded as a Bogon route object. The syntax of the address prefixes listed in a BOA uses a subset of the IP Address Delegation extension defined in [RFC3779]. The BOAIPAddressFamily cannot contain arbitrary address ranges, but in all other respects uses the same canonical format as the IP Address Delegation Extension. Within the BOAIPAddressFamily 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, as defined in[RFC3779]. 2.1.4. certificates The certificates field MUST be included, and MUST contain only the end entity (EE) certificate needed to validate this BOA. 2.1.5. crls The crls field MUST be omitted. 2.1.6. signerInfo 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 } Huston, et al. Expires May 2, 2009 [Page 6] Internet-Draft Bogon Attestations October 2008 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 BOA, 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 Signed Attributes are defined as: SignedAttributes ::= SET SIZE (1..MAX) OF Attribute Attribute ::= SEQUENCE { attrType OBJECT IDENTIFIER, attrValues SET OF AttributeValue } AttributeValue ::= ANY 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 BOA the attrValues must consist of only a single AttributeValue. Huston, et al. Expires May 2, 2009 [Page 7] Internet-Draft Bogon Attestations October 2008 2.1.6.4.1. Content-Type 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.[TBD] (matching the eContentType in the EncapsulatedContentInfo). 2.1.6.4.2. Message-Digest 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[RFC3852]. 2.1.6.4.3. Signing-Time Attribute The SigningTime Attribute MAY be present in a BOA. 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 BOA (as specified in Section 3). The attrType OID for the SigningTime attribute is 1.2.840.113549.1.9.5. The SigningTime attribute is defined as: id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 } 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. 2.1.6.4.4. BinarySigningTime Attribute 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 BinarySigningTime attribute is 1.2.840.113549.1.9.16.2.46. Huston, et al. Expires May 2, 2009 [Page 8] Internet-Draft Bogon Attestations October 2008 The BinarySigningTime attribute is defined as: id-aa-binarySigningTime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) aa(2) 46 } 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. 2.1.6.5. signatureAlgorithm The signatureAlgorithm MUST be RSA (rsaEncryption), the OID for which is 1.2.840.113549.1.1.1. 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. BOA Validation Before a relying party can use a BOA as a constrictor of a routing announcement, the relying party must use the RPKI to validate the BOA. To do this the relying party performs the following steps: 1. Verify that the BOA 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) Huston, et al. Expires May 2, 2009 [Page 9] Internet-Draft Bogon Attestations October 2008 b. The eContentType of the CMS object is id-ct-rpkiBOA (OID 1.2.840.113549.1.9.16.1.[TBD]) c. The version of the SignedData object is 3. d. The digestAlgorithm in the SignedData object is SHA-256 (OID 2.16.840.1.101.3.4.2.1). e. 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. f. The crls field in the SignedData object is omitted. g. The eContentType in the EncapsulatedContentInfo is rid-ct- rpkiBOA (OID 1.2.840.113549.1.9.16.1.[TBD]) h. The version of the BOA is 0. i. The addressFamily in the BOAIPAddressFamily is either IPv4 or IPv6 (0001 and 0002, respectively). j. The version of the SignerInfo is 3. k. The digestAlgorithm in the SignerInfo object is SHA-256 (OID 2.16.840.1.101.3.4.2.1). l. The signatureAlgorithm in the SignerInfo object is RSA (OID 1.2.840.113549.1.1.1). m. 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). . n. The unsignedAttrs field in the SignerInfo object is omitted. 2. Use the public key in the EE certificate to verify the signature on the BOA. 3. Verify that the EE certificate has an IP Address Delegation extension [RFC3779] and that the IP address prefixes in that extension exactly match the IP address prefixes in the BOA, and the AS numbers in that extension exactly match the AS numbers in the BOA. Huston, et al. Expires May 2, 2009 [Page 10] Internet-Draft Bogon Attestations October 2008 4. 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 [ID.sidr-res-certs] for more details.) Note that requiring an exact match between the IP address prefixes and AS's in a BOA and the IP address prefixes and AS's in the corresponding EE certificate does not place any limitations on BOA use. Since each EE certificate in the RPKI architecture is used to verify only a single BOA, it is natural to have the IP address prefixes in the certificate match those in the corresponding BOA. 4. BOA Use Practices BOAs are intended to allow relying parties a means of validating whether route origination information as described in a route advertisement refers to an IP address or AS number that has not been validly allocated for use in the routing system. Any party with a validly assigned Internet resource set and a CA certificate that describes this delegation can publish a BOA, independently of the actions of the actions of the party that assigned the resource set. BOAs are not hierarchically related. An Internet Registry SHOULD maintain a single BOA in relation to each parent registry that has assigned resources to this registry. An Internet Registry SHOULD maintain a regular issuance cycle for BOAs. For registries that operate on a day-to-day basis in terms of resource transactions, it is suggested that a local BOA management practice would be that a new BOA should be issued on a regular 24 hour basis. The corresponding EE certificate should have a validity period of no more than 72 hours from the time of issuance. Each time a new EE certificate for a BOA is issued the previous BOA's EE certificate should be revoked and the previous BOA removed from the publication repository. Parties that operate a local cache of RPKI objects should ensure that they refresh BOA objects at intervals 24 hours to ensure that they have the current BOA in the local cache. Huston, et al. Expires May 2, 2009 [Page 11] Internet-Draft Bogon Attestations October 2008 5. BOA Interpretation A BOA can be used to check an inter-domain routing advertisement ("route object") to determine if the origination information in the route object refers to invalid IP addresses or an invalid AS number. If a route object has an AS origination that refers to an AS number that is listed in a valid BOA, then the route object can be regarded as a Bogon object, and local policies that apply to Bogon AS's can be applied to the object. This holds whether or not the address prefix of the route object is described by a valid ROA or not. If a route object has an address prefix that is equal to, or is a more specific prefix of an IP address that is included in a valid BOA then the route object can be regarded as a Bogon object, and local policies that apply to Bogon AS's can be applied to the object, unless the address prefix and AS origination of the route object is also described by a valid ROA, in which case the BOA is to be disregarded. In other words, a valid ROA SHOULD infer a higher local trust preference than a BOA if a valid ROA and a valid BOA both exist that refer to the same address prefix. BOA interpretation in the context of validation of origination of route objects is described in [ID.sidr-roa-validation]. 6. Security Considerations There is no assumption of confidentiality for the data in a BOA; it is anticipated that BOAs 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 BOA, since the RPKI used for BOA validation provides authorization but not authentication. Although the BOA is a signed, application layer object, there is no intent to convey non-repudiation via a BOA. The purpose of a BOA is to convey an attestation by an address holder that there is no authority for the generation of a route object that refers to specified addresses or origination from specified AS's. The integrity of a BOA must be established in order to validate the authority of the Bogon Attestation. The BOA 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 BOA signer to authorize the attestation of specified IP addresses and AS's as Bogons is established through use of the address space and AS number PKI described in [ID.sidr-arch]. Specifically, a relying party must verify the signature on the BOA using an X.509 certificate issued under this PKI, and check that the prefix(es) in the BOA match Huston, et al. Expires May 2, 2009 [Page 12] Internet-Draft Bogon Attestations October 2008 those in the address space extension in the certificate. 7. IANA Considerations [None] 8. Acknowledgments The authors are indebted to the authors of Route Origin Authorization (ROA) [ID.sidr-roa-format], M. Lepinski, S. Kent and D. Kong, as much of the text used to define a BOA has been borrowed from the ROA format specification, and Russ Housley for clarification on the CMS profile. 9. Normative References [ID.sidr-arch] Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", draft-ietf-sidr-arch (work in progress), February 2008. [ID.sidr-res-certs] Huston, G., Michaleson, G., and R. Loomans, "A Profile for X.509 PKIX Resource Certificates", Internet Draft draft-ietf-sidr-res-certs, August 2008. [ID.sidr-roa-format] Lepinski, M., Kent, S., and D. Kong, "An Infrastructure to Support Secure Internet Routing", draft-ietf-sidr-roa-format (work in progress), July 2008. [ID.sidr-roa-validation] Huston, G. and G. Michaelson, "Validation of Route Origination in BGP using the Resource Certificate PKI", draft-ietf-sidr-roa-validation (work in progress), October 2008. [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, June 2004. [RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)", RFC 3852, July 2004. [RFC4055] Schaad, J., Kaliski, B., and R. Housley, "Additional Algorithms and Identifiers for RSA Cryptography for use in Huston, et al. Expires May 2, 2009 [Page 13] Internet-Draft Bogon Attestations October 2008 the Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 4055, June 2005. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, May 2008. Authors' Addresses Geoff Huston Asia Pacific Network Information Centre Email: gih@apnic.net URI: http://www.apnic.net George Michaelson Asia Pacific Network Information Centre Email: ggm@apnic.net URI: http://www.apnic.net Terry Manderson Email: terry@terrym.net Huston, et al. Expires May 2, 2009 [Page 14] Internet-Draft Bogon Attestations October 2008 Full 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. 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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. Huston, et al. Expires May 2, 2009 [Page 15]