Internet-Draft RPKI ASPA Profile November 2023
Azimov, et al. Expires 10 May 2024 [Page]
Network Working Group
Intended Status:
Standards Track
A. Azimov
E. Uskov
R. Bush
Internet Initiative Japan
J. Snijders
R. Housley
Vigil Security
B. Maddison

A Profile for Autonomous System Provider Authorization


This document defines a Cryptographic Message Syntax (CMS) protected content type for Autonomous System Provider Authorization (ASPA) objects for use with the Resource Public Key Infrastructure (RPKI). An ASPA is a digitally signed object through which the issuer (the holder of an Autonomous System identifier), can authorize one or more other Autonomous Systems (ASes) as its upstream providers. When validated, an ASPA's eContent can be used for detection and mitigation of route leaks.

Requirements Language

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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

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."

This Internet-Draft will expire on 10 May 2024.

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 [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. 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:

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


  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) } ;

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

  { TYPE ASProviderAttestation IDENTIFIED BY id-ct-ASPA }

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


ASID ::= INTEGER (0..4294967295)


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

3.1. version

The version number of the ASProviderAttestation that complies with this specification MUST be 1 and MUST be explicitly encoded.

3.2. customerASID

The customerASID field contains the AS number of the Customer Autonomous System that is the authorizing entity.

3.3. providers

The providers field contains the listing of ASes that are authorized as providers.

Each element contained in the providers field is an instance of ASID. Each ASID element contains the AS number of an AS that has been authorized by the customer AS as its provider or RS.

In addition to the constraints described by the formal ASN.1 definition, the contents of the providers field MUST satisfy the following constraints:

  • The CustomerASID value MUST NOT appear in any ASID in the providers field.

  • The elements of providers MUST be ordered in ascending numerical order.

  • Each value of ASID MUST be unique (with respect to the other elements of providers).

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.

5. IANA Considerations

5.1. SMI Security for S/MIME Module Identifier registry

Please add the id-mod-rpki-aspa-2023 to the SMI Security for S/MIME Module Identifier (1.2.840.113549. registry ( as follows:

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

5.2. SMI Security for S/MIME CMS Content Type registry

Please add the ASPA to the SMI Security for S/MIME CMS Content Type (1.2.840.113549. registry ( as follows:

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

5.3. RPKI Signed Object registry

Please add Autonomous System Provider Authorization to the RPKI Signed Object registry ( as follows:

    Name                                     | OID                         | Specification
    Autonomous System Provider Authorization | 1.2.840.113549.  | [RFC-to-be]

5.4. RPKI Repository Name Scheme registry

Please add an item for the Autonomous System Provider Authorization file extension to the "RPKI Repository Name Scheme" registry created by [RFC6481] as follows:

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

5.5. Media Type registry

The IANA is requested to register the media type application/rpki-aspa in the "Media Type" registry as follows:

   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 <>
   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.

7. Implementation status

This section is to be removed before publishing as an RFC.

This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in RFC 7942. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.

According to RFC 7942, "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".

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.


The following people made significant contributions to this document:

        Kotikalapudi Sriram
        USA National Institute of Standards and Technology


Normative References

Azimov, A., Bogomazov, E., Bush, R., Patel, K., Snijders, J., and K. Sriram, "BGP AS_PATH Verification Based on Autonomous System Provider Authorization (ASPA) Objects", Work in Progress, Internet-Draft, draft-ietf-sidrops-aspa-verification-16, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, DOI 10.17487/RFC3779, , <>.
Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, RFC 5652, DOI 10.17487/RFC5652, , <>.
Huston, G., Loomans, R., and G. Michaelson, "A Profile for Resource Certificate Repository Structure", RFC 6481, DOI 10.17487/RFC6481, , <>.
Huston, G., "The Profile for Algorithms and Key Sizes for Use in the Resource Public Key Infrastructure (RPKI)", RFC 6485, DOI 10.17487/RFC6485, , <>.
Lepinski, M., Chi, A., and S. Kent, "Signed Object Template for the Resource Public Key Infrastructure (RPKI)", RFC 6488, DOI 10.17487/RFC6488, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
ITU-T, "Information technology - Abstract Syntax Notation One (ASN.1): Specification of basic notation", ITU-T Recommendation X.680, .
ITU-T, "Information Technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)", ITU-T Recommendation X.690, .

Informative References

Bruijnzeels, T., "krill", , <>.
Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, , <>.
Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480, , <>.
Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker, "Internet Exchange BGP Route Server", RFC 7947, DOI 10.17487/RFC7947, , <>.
Hoffman, M., "routinator", , <>.
Harrison, T., "rpki-aspa-demo", , <>.
Snijders, J., "rpki-client", , <>.
de Kock, T., "rpki-commons", , <>.
Puzanov, M., "rpki-prover", , <>.

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.


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://
EE Subject info access:      rsync://
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

Alexander Azimov
Eugene Uskov
Randy Bush
Internet Initiative Japan
Job Snijders
Russ Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
United States of America
Ben Maddison
Cape Town
South Africa