A Profile for Autonomous System Provider Authorization

Status of This Memo

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Table of Contents

1. Introduction

The primary purpose of the Resource Public Key Infrastructure (RPKI) is to improve routing security [RFC6480]. As part of this infrastructure, a mechanism is needed to facilitate holders of Autonomous System (AS) identifiers in their capacity as Customer to authorize other ASes as their Provider(s). A Provider AS (PAS) is a network that:¶

1. offers its customers outbound (customer to Internet) data traffic connectivity and/or¶

2. further propagates in all directions (towards providers, lateral peers, and customers) any BGP Updates that the customer may send.¶

The digitally signed Autonomous System Provider Authorization (ASPA) object described in this document provides the above-mentioned authorization mechanism.¶

An ASPA object is a cryptographically verifiable attestation signed by the holder of an Autonomous System identifier (hereafter called the "Customer AS", or CAS). An ASPA contains a list of one or more ASes, each listing meaning the listed AS is authorized to act as Provider network. When the CAS has multiple Providers, all Provider ASes are listed in the ASPA, including any non-transparent Internet Exchange Point (IXP) Route Server (RS) ASes. The common case for RS ASes at IXPs is to operate transparently (see Section 2.2.2.1 [RFC7947]), and in those instances the ASNs of IXP Route Servers are not listed as PAS in ASPAs.¶

The BGP Roles that an Autonomous System (AS) may have in its peering relationships with eBGP neighbors are discussed in [I-D.ietf-sidrops-aspa-verification]. The details of ASPA registration requirements for ASes in different scenarios are also specified in that document. In addition, the procedures for verifying AS_PATHs in BGP UPDATE messages using Validated ASPA Payloads (VAPs) are described in that document.¶

This CMS [RFC5652] protected content type definition conforms to the [RFC6488] template for RPKI signed objects. In accordance with Section 4 of [RFC6488], this document defines:¶

1. The object identifier (OID) that identifies the ASPA signed object. This OID appears in the eContentType field of the encapContentInfo object as well as the content-type signed attribute within the signerInfo structure.¶

2. The ASN.1 syntax for the ASPA content, which is the payload signed by the CAS. The ASPA content is encoded using the ASN.1 [X.680] Distinguished Encoding Rules (DER) [X.690].¶

3. The steps required to validate an ASPA beyond the validation steps specified in [RFC6488].¶

2. ASPA Content Type

The content-type for an ASPA is defined as id-ct-ASPA, which has the numerical value of 1.2.840.113549.1.9.16.1.49. This OID MUST appear both within the eContentType in the encapContentInfo structure as well as the content-type signed attribute within the signerInfo structure (see [RFC6488]).¶

3. ASPA eContent

The content of an ASPA identifies the Customer AS (CAS) as well as the Set of Provider ASes (SPAS) that are authorized by the CAS to be its Providers.¶

A user registering ASPA(s) must be cognizant of Sections 2, 3, and 4 of [I-D.ietf-sidrops-aspa-verification] and the user (or their software tool) must comply with the ASPA registration recommendations in Section 4 of that document.¶

It is highly recommended that for a given Customer AS, a single ASPA object be maintained which contains all providers, including any non-transparent RS ASes. Such a practice helps prevent race conditions during ASPA updates. Otherwise, said race conditions might affect route propagation. The software that provides hosting for ASPA records SHOULD support enforcement of this recommendation. In the case of the transition process between different CA registries, the ASPA records SHOULD be kept identical in all registries in terms of their authorization contents.¶

The eContent of an ASPA is an instance of ASProviderAttestation, formally defined by the following ASN.1 [X.680] module:¶

RPKI-ASPA-2023
  { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
     pkcs-9(9) smime(16) modules(0) id-mod-rpki-aspa-2023(TBD) }

DEFINITIONS EXPLICIT TAGS ::=
BEGIN

IMPORTS
  CONTENT-TYPE
  FROM CryptographicMessageSyntax-2010  -- RFC 6268
    { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
       pkcs-9(9) smime(16) modules(0) id-mod-cms-2009(58) } ;

id-ct-ASPA OBJECT IDENTIFIER ::=
  { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
    pkcs-9(9) id-smime(16) id-ct(1) aspa(49) }

ct-ASPA CONTENT-TYPE ::=
  { TYPE ASProviderAttestation IDENTIFIED BY id-ct-ASPA }

ASProviderAttestation ::= SEQUENCE {
  version [0]   INTEGER DEFAULT 0,
  customerASID  ASID,
  providers     ProviderASSet }

ProviderASSet ::= SEQUENCE (SIZE(1..MAX)) OF ASID

ASID ::= INTEGER (0..4294967295)

END

Note that this content appears as the eContent within the encapContentInfo as specified in [RFC6488].¶

4. ASPA Validation

Before a relying party can use an ASPA to validate a routing announcement, the relying party MUST first validate the ASPA object itself. To validate an ASPA, the relying party MUST perform all the validation checks specified in [RFC6488] as well as the following additional ASPA-specific validation steps.¶

• The Autonomous System Identifier Delegation Extension [RFC3779] MUST be present in the end-entity (EE) certificate (contained within the ASPA), and the Customer ASID in the ASPA eContent MUST be contained within the set of AS numbers specified by the EE certificate's Autonomous System Identifier Delegation Extension.¶

• The EE certificate's Autonomous System Identifier Delegation Extension MUST NOT contain any "inherit" elements.¶

• The IP Address Delegation Extension [RFC3779] MUST be absent.¶

5. IANA Considerations

    Decimal   | Description                   | Specification
    -----------------------------------------------------------
    TBD2      | id-mod-rpki-aspa-2023         | [RFC-to-be]

    Decimal   | Description                   | Specification
    -----------------------------------------------------------
    49        | id-ct-ASPA                    | [RFC-to-be]

    Name                                     | OID                         | Specification
    --------------------------------------------------------------------------------------
    Autonomous System Provider Authorization | 1.2.840.113549.1.9.16.1.49  | [RFC-to-be]

   Filename
   Extension  RPKI Object                               Reference
   --------------------------------------------------------------------------------------
      .asa    Autonomous System Provider Authorization  [RFC-to-be]

   Type name: application
   Subtype name: rpki-aspa
   Required parameters: N/A
   Optional parameters: N/A
   Encoding considerations: binary
   Security considerations: Carries an RPKI ASPA [RFC-to-be].
       This media type contains no active content. See
       Section 4 of [RFC-to-be] for further information.
   Interoperability considerations: None
   Published specification: [RFC-to-be]
   Applications that use this media type: RPKI operators
   Additional information:
     Content: This media type is a signed object, as defined
         in [RFC6488], which contains a payload of a list of
         AS identifers as defined in [RFC-to-be].
     Magic number(s): None
     File extension(s): .asa
     Macintosh file type code(s):
   Person & email address to contact for further information:
     Job Snijders <job@fastly.com>
   Intended usage: COMMON
   Restrictions on usage: None
   Change controller: IETF

6. Security Considerations

The security considerations of [RFC6481], [RFC6485], and [RFC6488] also apply to ASPAs.¶

8. Acknowledgments

The authors would like to thank Keyur Patel for helping kick-start the ASPA profile project, Ties de Kock & Tim Bruijnzeels for suggesting that the ProviderASSet be in a canonical form, and Claudio Jeker & Martin Hoffman for review and several suggestions for improvements.¶

Appendix A. Example ASPA eContent Payload

Below an example of a DER encoded ASPA eContent is provided with annotation following the '#' character.¶

$ echo 301da00302010102023cca301202020b620202205b020300c790020303259e \
  | xxd -r -ps | openssl asn1parse -inform DER -dump -i
    0:d=0  hl=2 l=  29 cons: SEQUENCE
    2:d=1  hl=2 l=   3 cons:  cont [ 0 ]
    4:d=2  hl=2 l=   1 prim:   INTEGER           :01
    7:d=1  hl=2 l=   2 prim:  INTEGER           :3CCA    # Customer ASID 15562
   11:d=1  hl=2 l=  18 cons:  SEQUENCE
   13:d=2  hl=2 l=   2 prim:   INTEGER           :0B62   # ProviderAS 2914
   17:d=2  hl=2 l=   2 prim:   INTEGER           :205B   # ProviderAS 8283
   21:d=2  hl=2 l=   3 prim:   INTEGER           :C790   # ProviderAS 51088
   26:d=2  hl=2 l=   3 prim:   INTEGER           :03259E # ProviderAS 206238

Below is a complete Base64 [RFC4648] encoded RPKI ASPA Signed Object.¶
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The above should decode as following:¶

Object SHA256 hash:          s25yLaks3OXBzJcW3ZgvlLDiPUpyZbQk2jDHaPDgn1w=
EE Subject key identifier:   E6:6F:34:7F:06:30:B3:FD:C5:88:50:FB:26:24:23:02:A6:75:45:84
EE Certificate issuer:       /CN=caa805dbac364749b9b115590ab6ef0f970cdbd8
EE Certificate serial:       A1C7752FF8B1D2E01F
EE Authority key identifier: CA:A8:05:DB:AC:36:47:49:B9:B1:15:59:0A:B6:EF:0F:97:0C:DB:D8
EE Authority info access:    rsync://rpki.ripe.net/repository/DEFAULT/yqgF26w2R0m5sRVZCrbvD5cM29g.cer
EE Subject info access:      rsync://chloe.sobornost.net/rpki/RIPE-nljobsnijders/5m80fwYws_3FiFD7JiQjAqZ1RYQ.asa
CMS Signing time:            Wed 07 Jun 2023 09:08:41 +0000
EE notBefore:                Wed 07 Jun 2023 09:08:14 +0000
EE notAfter:                 Thu 06 Jun 2024 09:08:14 +0000

ASPA eContent:
  Customer AS:               15562
  Provider Set:              1: AS: 2914
                             2: AS: 8283
                             3: AS: 51088
                             4: AS: 206238

Authors' Addresses