ROA profile: A Profile for Route Origin Authorizations (ROAs)

Internet Engineering Task Force (IETF)                       M. Lepinski
Request for Comments: 6482                                       S. Kent
Category: Standards Track                                        D. Kong
ISSN: 2070-1721                                         BBN Technologies
                                                           February 2012


            A Profile for Route Origin Authorizations (ROAs)

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 one or
   more prefixes within the address block.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by
   the Internet Engineering Steering Group (IESG).  Further
   information on Internet Standards is available in Section 2 of
   RFC 5741.

   Information about the current status of this document, any
   errata, and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6482.

Copyright Notice

   Copyright (c) 2012 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
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   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................3
   2. The ROA Content-Type ............................................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. Acknowledgments .................................................6
   7. References ......................................................6
      7.1. Normative References .......................................6
      7.2. Informative References .....................................6
    Appendix A: ASN.1  Module..........................................8

1. Introduction

   The primary purpose of the Resource Public Key Infrastructure (RPKI)
   is to improve routing security.  (See [RFC6480] 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
   [RFC6488], 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 [RFC6488]), this document
   defines:

      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 content-type 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.)
         The ROA eContent is ASN.1 encoded using the Distinguished
         Encoding Rules (DER) [X.690].

      3. An additional step required to validate ROAs (in addition to
         the validation steps specified in [RFC6488]).

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 [RFC6488]; 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 [RFC6487]; thus,
   familiarly with that 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 Content-Type

   The content-type 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 content-type signed attribute
   in the signerInfo object (see [RFC6488]).

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
   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 [RFC6488]).

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.

   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 the 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 with a maximum length of 26.  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
   the exact 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 a minimum length of 24 and a maximum length of 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 [RFC6488] as well as the following additional
   ROA-specific validation step.

   o  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 the 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
   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
   [RFC6488] also apply to ROAs.  Additionally, the signed object
   profile uses the CMS signed message format for integrity; thus, ROAs
   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 [RFC6480].  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 certificate's address space extension.

6.  IANA Considerations

   IANA has registered the following RPKI Signed Object:

   ROA    1.2.840.113549.1.9.16.1.24    [RFC6482]

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.

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 (CMS)", STD 70,
             RFC 5652, September 2009.

   [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
             Addresses and AS Identifiers", RFC 3779, June 2004.

   [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.

   [RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
             X.509 PKIX Resource Certificates", RFC 6487, February 2012.

   [RFC6488] Lepinski, M., Chi, A., and S. Kent, "Signed Object Template
             for the Resource Public Key Infrastructure (RPKI)", RFC
             6488, February 2012.

   [X.690]   ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
             Information technology - ASN.1 encoding rules:
             Specification of Basic Encoding Rules (BER), Canonical
             Encoding Rules (CER) and Distinguished Encoding Rules
             (DER).

8.2.  Informative References

   [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
             Secure Internet Routing", RFC 6480, February 2012.

Appendix A: ASN.1 Module

   This normative appendix provides an ASN.1 module that specifies the
   ROA content in ASN.1 syntax.

   RPKI-ROA { 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

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