Secure Inter-Domain Routing (sidr)                         Lepinski, M.
Internet Draft                                                 Kent, S.
Expires: January 2008                                          Kong, D.
Intended Status: Proposed Standard                     BBN Technologies
                                                              July 2007

             A Profile for Route Origin Authorizations (ROAs)
                        draft-ietf-sidr-roa-format-01.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.

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].



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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.




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   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.


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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


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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.





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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.








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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 use the resource PKI to validate
   the ROA. To do this the relying party performs 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).


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       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 that has a Subject Key Identifier (SKI)
      that 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(es), 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


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   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.


































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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-
             01.txt, July, 2007 (work in progress).

   [RESCERT] Huston, G., Michaelson, G., and Loomans, R., ''A Profile for
             X.509 PKIX Resource Certificates,'' draft-ietf-sidr-res-
             certs-07.txt, June, 2007 (work in progress).















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Author's Addresses

   Matthew 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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   This document is subject to the rights, licenses and restrictions
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