A Profile for Autonomous System Provider Authorization

The primary purpose of the Resource Public Key Infrastructure (RPKI) is to improve routing security . 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. See for a specification how to use Validated ASPA Payloads (VAPs) to filter BGP UPDATE messages. 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 lists 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 that provide service to the CAS are listed in the ASPA, including any non-transparent Internet Exchange Point (IXP) Route Server (RS) ASes. The common case for Route Servers (RS) at Internet Exchange Points is to operate transparently (see Section 2.2.2.1 ), thus usually, the ASNs of IX Route Servers are not listed as PAS in ASPAs. The ASPA content type definition conforms to the template for RPKI signed objects. In accordance with Section 4 of , 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 Distinguished Encoding Rules (DER) . The steps required to validate an ASPA beyond the validation steps specified in .

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 ).

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. If a Customer AS is connected to multiple transit providers/non-transparent route servers, all Provider ASes MUST be registered in a single ASPA object. This rule is important to avoid possible race conditions during updates of ASPAs. The eContent of an ASPA is an instance of ASProviderAttestation, formally defined by the following ASN.1 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-2022(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) 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 ProviderAS ProviderAS ::= SEQUENCE { providerASID ASID, afiLimit AddressFamilyIdentifier OPTIONAL } ASID ::= INTEGER (0..4294967295) AddressFamilyIdentifier ::= OCTET STRING (SIZE (2)) END Note that this content appears as the eContent within the encapContentInfo as specified in .

The version number of the ASProviderAttestation MUST be v0.

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

The providers field contains the listing of ASes that are authorized as providers or route servers in the specified address family. Each element contained in the providers field is an instance of ProviderAS. 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 providerASID field. The elements of providers MUST be ordered in ascending numerical order by the value of the providerASID field. Each value of providerASID MUST be unique (with respect to the other elements of providers).

The providerASID field contains the AS number of an AS that has been authorized by the customer AS as its provider or RS in the specified address family.

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 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 as well as the following additional ASPA-specific validation steps. The Autonomous System Identifier Delegation Extension 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 MUST be absent.

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 | [RFC-to-be]

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 | [RFC-to-be]

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 | [RFC-to-be]

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

The IANA is requested to register the media type application/rpki-aspa in the "Media Type" registry as follows: Intended usage: COMMON Restrictions on usage: None Change controller: IETF ]]>

While it is not technically enforcable, it is highly recommended that for a given Customer AS, a single ASPA object be maintained which contains all providers/route servers. Administrating all providers in a single object helps 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 in terms of their authorization contents.

Implementation status 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 (version 8.0 and higher), written in C was provided by Job Snijders from Fastly.
A signer and decoder implementation written in Python was provided by Ben Maddison from Workonline.
A signer implementation 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 in RPSTIR2 validating objects produced by Tim Bruijnzeels.
A signer implementation written in PHP based on OpenSSL was provided by Koen van Hove.
A signer implementation written in Perl based on OpenSSL was provided by Tom Harrison from APNIC.

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 Kotikalapudi Sriram & Claudio Jeker for review and several suggestions for improvements.

Key words for use in RFCs to Indicate Requirement Levels In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. X.509 Extensions for IP Addresses and AS Identifiers This document defines two X.509 v3 certificate extensions. The first binds a list of IP address blocks, or prefixes, to the subject of a certificate. The second binds a list of autonomous system identifiers to the subject of a certificate. These extensions may be used to convey the authorization of the subject to use the IP addresses and autonomous system identifiers contained in the extensions. [STANDARDS-TRACK] Cryptographic Message Syntax (CMS) This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK] A Profile for Resource Certificate Repository Structure This document defines a profile for the structure of the Resource Public Key Infrastructure (RPKI) distributed repository. Each individual repository publication point is a directory that contains files that correspond to X.509/PKIX Resource Certificates, Certificate Revocation Lists and signed objects. This profile defines the object (file) naming scheme, the contents of repository publication points (directories), and a suggested internal structure of a local repository cache that is intended to facilitate synchronization across a distributed collection of repository publication points and to facilitate certification path construction. [STANDARDS-TRACK] The Profile for Algorithms and Key Sizes for Use in the Resource Public Key Infrastructure (RPKI) This document specifies the algorithms, algorithms' parameters, asymmetric key formats, asymmetric key size, and signature format for the Resource Public Key Infrastructure (RPKI) subscribers that generate digital signatures on certificates, Certificate Revocation Lists, and signed objects as well as for the relying parties (RPs) that verify these digital signatures. [STANDARDS-TRACK] Signed Object Template for the Resource Public Key Infrastructure (RPKI) This document defines a generic profile for signed objects used in the Resource Public Key Infrastructure (RPKI). These RPKI signed objects make use of Cryptographic Message Syntax (CMS) as a standard encapsulation format. [STANDARDS-TRACK] Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Information technology - Abstract Syntax Notation One (ASN.1): Specification of basic notation 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 The Base16, Base32, and Base64 Data Encodings This document describes the commonly used base 64, base 32, and base 16 encoding schemes. It also discusses the use of line-feeds in encoded data, use of padding in encoded data, use of non-alphabet characters in encoded data, use of different encoding alphabets, and canonical encodings. [STANDARDS-TRACK] An Infrastructure to Support Secure Internet Routing This document describes an architecture for an infrastructure to support improved security of Internet routing. The foundation of this architecture is a Resource Public Key Infrastructure (RPKI) that represents the allocation hierarchy of IP address space and Autonomous System (AS) numbers; and a distributed repository system for storing and disseminating the data objects that comprise the RPKI, as well as other signed objects necessary for improved routing security. As an initial application of this architecture, the document describes how a legitimate holder of IP address space can explicitly and verifiably authorize one or more ASes to originate routes to that address space. Such verifiable authorizations could be used, for example, to more securely construct BGP route filters. This document is not an Internet Standards Track specification; it is published for informational purposes. Internet Exchange BGP Route Server This document outlines a specification for multilateral interconnections at Internet Exchange Points (IXPs). Multilateral interconnection is a method of exchanging routing information among three or more External BGP (EBGP) speakers using a single intermediate broker system, referred to as a route server. Route servers are typically used on shared access media networks, such as IXPs, to facilitate simplified interconnection among multiple Internet routers. BGP AS_PATH Verification Based on Resource Public Key Infrastructure (RPKI) Autonomous System Provider Authorization (ASPA) Objects Yandex Qrator Labs Internet Initiative Japan & Arrcus, Inc. Arrcus Fastly USA National Institute of Standards and Technology This document defines the semantics of an Autonomous System Provider Authorization object in the Resource Public Key Infrastructure to verify the Border Gateway Protocol (BGP) AS_PATH attribute of advertised routes. This type of AS_PATH verification is primarily intended for detection and mitigation of route leaks. It also to some degree provides protection against forged-origin prefix hijacks. rpkimancer-aspa Workonline rpki-client Fastly Krill NLnetLabs RPSTIR2 ZDNS RPKI ASPA Demo APNIC Relying Party Resiliency Platform Independent Address Family Numbers IANA

Example ASPA eContent Payload Below an example of a DER encoded ASPA eContent is provided with annotation following the '#' character. Below is a complete Base64 encoded RPKI ASPA Signed Object. The above should decode as following: