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.¶
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"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.¶
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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:¶
offers its customers outbound (customer to Internet) data traffic connectivity and/or¶
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 126.96.36.199 [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:¶
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.¶
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].¶
The steps required to validate an ASPA beyond the validation steps specified in [RFC6488].¶
The content-type for an ASPA is defined as id-ct-ASPA, which has the numerical value of 1.2.840.1135188.8.131.52.1.49.
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]).¶
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:¶
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.
This specification only supports IPv4 and IPv6.
Therefore, the value MUST be either 0001 or 0002, as specified in the Address Family Numbers registry [IANA-AF] maintained by IANA.¶
If omitted, the authorization is valid for both IPv4 and IPv6 announcements.¶
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.¶
Please add the id-mod-rpki-aspa-2022 to the SMI Security for S/MIME Module Identifier (1.2.840.1135184.108.40.206.0) registry (https://www.iana.org/assignments/smi-numbers/smi-numbers.xml#security-smime-0) as follows:¶
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
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 <firstname.lastname@example.org>
Intended usage: COMMON
Restrictions on usage: None
Change controller: IETF
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".¶
A validator implementation [rpki-client] (version 8.0 and higher), written in C was provided by Job Snijders from Fastly.¶
A signer and decoder implementation [rpkimancer] written in Python was provided by Ben Maddison from Workonline.¶
A signer implementation [krill] written in Rust was provided by Tim Bruijnzeels from NLnetLabs.¶
At IETF114 Ties de Kock from RIPE NCC shared a signer implementation had been developed internally.¶
Di Ma reported success [rpstir2] in RPSTIR2 validating objects produced by Tim Bruijnzeels.¶
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 for review and several suggestions for improvements.¶
Below are a number of examples to demonstrate how one (or more) ASPA eContent Payloads are to be transformed into RTR ASPA PDUs.
See section 5.12 of [I-D.ietf-sidrops-8210bis] for the specification of ASPA PDUs.¶
Note that two PDUs are always generated per Customer ASID: one with AFI Flags = IPv4 and one with AFI Flags = IPv6.¶