Internet-Draft ASPA Profile July 2022
Azimov, et al. Expires 6 January 2023 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-ietf-sidrops-aspa-profile-08
Published:
Intended Status:
Standards Track
Expires:
Authors:
A. Azimov
Yandex
E. Uskov
JetLend
R. Bush
Internet Initiative Japan
K. Patel
Arrcus
J. Snijders
Fastly
R. Housley
Vigil Security

A Profile for Autonomous System Provider Authorization

Abstract

This document defines a standard profile for Autonomous System Provider Authorization in the Resource Public Key Infrastructure. An Autonomous System Provider Authorization is a digitally signed object that provides a means of validating that a Customer Autonomous System holder has authorized members of Provider set to be its upstream providers or provide route server service at internet exchange point. For the Providers it means that they are legal to send prefixes received from the Customer Autonomous System in all directions including providers and peers.

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 https://datatracker.ietf.org/drafts/current/.

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 6 January 2023.

Table of Contents

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 infrastructure, a mechanism is needed to validate that a AS has permission from a Customer AS (CAS) holder to send routes in all directions. The digitally signed Autonomous System Provider Authorization (ASPA) object provides this validation mechanism.

The ASPA uses the template for RPKI digitally signed objects [RFC6488], which defines a Cryptographic Message Syntax (CMS) [RFC5652] wrapper for the ASPA content as well as a generic validation procedure for RPKI signed objects. As ASPAs need to be validated with RPKI certificates issued by the current infrastructure, we assume the mandatory-to-implement algorithms in [RFC6485], or its successor.

To complete the specification of the ASPA (see 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 [X680] Distinguished Encoding Rules (DER) [X690].
  3. The steps required to validate an ASPA beyond the validation steps specified in [RFC6488]).

2. The 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. The ASPA eContent

The content of an ASPA identifies the Customer AS (CAS) as well as the Set of Provider ASes (SPAS) that are authorized to further propagate announcements received from the customer.

Not all route servers at internet exchange points are transparent, e.g. in some cases they are present in the ASPATH. In this case route server AS is acting as provider AS, which propagates routes between its customers. Thus, a customer MUST add both upstream providers and route sever AS it is connected to its SPAS.

If customer is connected to multiple transit providers/route servers they MUST be registered in a single ASPA object. This rule is important to avoid possible race conditions during updates.

The eContent of an ASPA is an instance of ASProviderAttestation, formally defined by the following ASN.1 [X680] module:

RPKI-ASPA-2022
  { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
     pkcs-9(9) smime(16) modules(0) id-mod-rpki-aspa-2020(TBD) }

DEFINITIONS IMPLICIT 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) 49 }

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

ASProviderAttestation ::= SEQUENCE {
  version [0]   ASPAVersion DEFAULT v0,
  customerASID  ASID,
  providers     ProviderASSet }

ASPAVersion ::= INTEGER  { v0(0) }

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

ProviderAS ::= SEQUENCE {
  providerASID  ASID,
  afiLimit      AddressFamilyIdentifier OPTIONAL }

ASID ::= INTEGER

AddressFamilyIdentifier ::= OCTET STRING (SIZE (2))

END

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

3.1. version

The version number of the ASProviderAttestation MUST be v0.

3.2. customerASID

The customerASID field contains the AS number of the Autonomous System (AS) that authorizes a collection of provider ASes (as listed in the providerASSet) to propagate prefixes in the specified address family to other ASes.

3.3. providers

The providers field contains the listing of ASes that are authorized to further propagate announcements in the specified address family received from the customer.

Each element contained in the providers field is an instance of ProviderAS.

3.3.1. ProviderAS

3.3.1.1. providerASID

The providerASID field contains the AS number of an AS that has been authorized by the customer AS to propagate prefixes in the specified address family to other ASes.

3.3.1.2. afiLimit

The afiLimit field optionally constrains the authorization given to the provider AS to a single address family.

If present, it contains the two-octet Address Family Identifier (AFI) for which the relation between the customer and provider is authorized. AFI values are specified in [IANA-AF].

If omitted, the authorization is valid for both IPv4 and IPv6 announcements.

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 step.

5. IANA Considerations

Please add the id-mod-rpki-aspa-2022 to the SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0) registry (https://www.iana.org/assignments/smi-numbers/smi-numbers.xml#security-smime-0) as follows:

    Decimal   | Description                   | Specification
    -----------------------------------------------------------
    TBD2      | id-mod-rpki-aspa-2022         | [ThisRFC]

Please add the ASPA to the SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1) registry (https://www.iana.org/assignments/smi-numbers/smi-numbers.xml#security-smime-1) as follows:

    Decimal   | Description                   | Specification
    -----------------------------------------------------------
    49        | id-ct-ASPA                    | [ThisRFC]

Please add Autonomous System Provider Authorization to the RPKI Signed Object registry (https://www.iana.org/assignments/rpki/rpki.xhtml#signed-objects) as follows:

    Name                                     | OID                         | Specification
    --------------------------------------------------------------------------------------
    Autonomous System Provider Authorization | 1.2.840.113549.1.9.16.1.49  | [ThisRFC]

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


   Filename
   Extension  RPKI Object                               Reference
   --------------------------------------------------------------------------------------
      .asa    Autonomous System Provider Authorization  [draft-ietf-sidrops-aspa-profile]

6. Security Considerations

While it's not restricted, but it's highly recommended maintaining for selected Customer AS a single ASPA object that covers all connected providers/route servers. Such policy should prevent race conditions during ASPA updates that might affect prefix propagation. The software that provides hosting for ASPA records SHOULD support enforcement of this rule. In the case of the transition process between different CA registries, the ASPA records SHOULD be kept identical in all registries.

7. Acknowledgments

The authors would like to thank Ben Maddison for substantial review and contributions to the ASN.1 specification.

8. References

8.1. Normative References

[IANA-AF]
IANA, "Address Family Numbers", <https://www.iana.org/assignments/address-family-numbers/address-family-numbers.xhtml>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3779]
Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, DOI 10.17487/RFC3779, , <https://www.rfc-editor.org/info/rfc3779>.
[RFC5652]
Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, RFC 5652, DOI 10.17487/RFC5652, , <https://www.rfc-editor.org/info/rfc5652>.
[RFC6481]
Huston, G., Loomans, R., and G. Michaelson, "A Profile for Resource Certificate Repository Structure", RFC 6481, DOI 10.17487/RFC6481, , <https://www.rfc-editor.org/info/rfc6481>.
[RFC6485]
Huston, G., "The Profile for Algorithms and Key Sizes for Use in the Resource Public Key Infrastructure (RPKI)", RFC 6485, DOI 10.17487/RFC6485, , <https://www.rfc-editor.org/info/rfc6485>.
[RFC6488]
Lepinski, M., Chi, A., and S. Kent, "Signed Object Template for the Resource Public Key Infrastructure (RPKI)", RFC 6488, DOI 10.17487/RFC6488, , <https://www.rfc-editor.org/info/rfc6488>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[X680]
ITU-T, "Information technology -- Abstract Syntax Notation One (ASN.1): Specification of basic notation", ITU-T Recommendation X.680, .
[X690]
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, .

8.2. Informative References

[RFC6480]
Lepinski, M. and S. Kent, "An Infrastructure to Support Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480, , <https://www.rfc-editor.org/info/rfc6480>.

Authors' Addresses

Alexander Azimov
Yandex
Eugene Uskov
JetLend
Randy Bush
Internet Initiative Japan
Keyur Patel
Arrcus, Inc.
Job Snijders
Fastly
Amsterdam
Russ Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
United States of America