]> Zhongguancun Laboratory

Beijing China liq23@zgclab.edu.cn

Tsinghua University

Beijing China xuke@tsinghua.edu.cn

Tsinghua University

Beijing China zhuotaoliu@tsinghua.edu.cn

Tsinghua University

Beijing China qli01@tsinghua.edu.cn

Tsinghua University

Beijing China jianping@cernet.edu.cn

Operations and Management SIDR Operations This document defines a "Signed MOAS Group", a Cryptographic Message Syntax (CMS) protected content type for use with the Resource Public Key Infrastructure (RPKI) to authenticate the collective announcement of IP prefixes by Multiple Origin Autonomous System (MOAS). The Signed MOAS Group includes two parts: an IP prefix and a list of Autonomous Systems (ASes) authorized to announce the prefix. At least one of these ASes SHOULD be authorized to announce the prefix by the prefix owner through a Route Origin Authorization (ROA). The validation of a Signed MOAS Group confirms that the authorized ASes and other listed ASes have collectively agreed to announce the prefix, ensuring that the announcement is legitimate, accurate, and consensually authorized.

Introduction This document defines a "Signed MOAS Group", a Cryptographic Message Syntax (CMS) protected content type to carry an IP prefix and a list of Autonomous Systems (ASes) authorized to announce this prefix. The Signed MOAS Group allows multiple ASes to collaboratively and securely announce an IP prefix, supporting scenarios such as business partnerships, traffic engineering, and DDoS protection services. A Signed MOAS Group object consists of two components: an IP prefix and a list of Autonomous Systems (ASes) intended to announce the prefix collaboratively, which allows other RPKI-validating routing entities to audit the collection of announcements from multiple originating AS. At least one AS in the AS list SHOULD be authorized to announce the prefix by the prefix owner through a corresponding ROA, which means the IP prefix in the ROA SHOULD match the IP prefix in the Signed MOAS Group and the AS number in the ROA SHOULD appear in the AS list. The object is collectively signed by the listed ASes using a multi-signature technique, and the aggregated global signature is attached to the Signed MOAS Group object, ensuring that the announcement could be legitimately proposed by all participating ASes and is verifiable by any RPKI-validating remote routing entities. To validate a Signed MoasGroup object, a relying party (RP) aggregates the public keys of all ASes in the AS list into a global public key, which is subsequently used to verify the multi-signature of the Signed MOAS Group object. There are three possible validation outcomes. First, if the Signed MOAS Group is verified and at least one corresponding ROA is found, it is considered valid. Second, if the Signed MOAS Group is verified but no corresponding ROA is found, it is deemed suspicious. Lastly, if the Signed MOAS Group cannot be verified, it is considered invalid. The Signed MOAS Group provides a mechanism for securely managing multi-origin AS announcements, offering a robust and flexible solution to handle modern routing requirements. Any prefixes announced by ASes that are not included in a ROA or a validated Signed MOAS Group SHOULD be regarded as invalid, though their handling is subject to local routing policies. The intent is to offer a secure and authenticated method for managing MOAS scenarios, enhancing the overall security and integrity of the routing system. Signed MOAS Group objects follow the Signed Object Template for the RPKI .

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 when, and only when, they appear in all capitals, as shown here.

Signed MoasGroup eContentType The eContentType for a MoasGroup is defined as id-ct-rpkiSignedMoasGroup, with Object Identifier (OID) 1.2.840.113549.1.9.16.1.TBD. This OID MUST appear within both the eContentType in the encapContentInfo object and the ContentType signed attribute in the signerInfo object (see ).

Signed MoasGroup eContent The content of a MoasGroup is a single IP prefix and a list of ASes. A MoasGroup is formally defined as follows:

Version The version number of the RpkiSignedMoasGroup MUST be 0.

asList This field contains the AS numbers that are intended to originate routes to the given IP address prefixes. The AS numbers that are authorized by ROA SHOULD be put in front of other AS numbers. The AS numbers MUST NOT duplicate.

ipAddressPrefix This field contains an AddressFamilyIPAddress which contains one instance of addressFamily and one instance of prefix.

addressFamily This field contains an OCTET STRING which is either '0001'H (IPv4) or '0002'H (IPv6).

prefix This field contains a BIT STRING, its length bounded through the addressFamily field. The type is a BIT STRING, see for more information.

Signed MoasGroup Validation To validate a MoasGroup, the relying party MUST perform all the validation checks specified in . In addition, the RP MUST perform the following validation steps:

1. The contents of the CMS eContent field MUST conform to all of the constraints described in Section .
2. The RP MUST verify the signatures of the Signed MOAS Group. This involves aggregating the public keys of all ASes listed in the AS list into a global public key. The aggregated global public key is subsequently used to verify the global signature attached to the Signed MOAS Group object.
3. The RP MUST check for the existence of a corresponding ROA for the IP prefix in the Signed MOAS Group. The IP prefix in the ROA MUST match the IP prefix in the Signed MOAS Group, and the AS number in the ROA MUST appear in the AS list.
4. A Signed MOAS Group has three possible validation outcomes. (1) Valid: If the Signed MOAS Group is verified and at least one corresponding ROA is found, it is considered valid. (2) Suspicious: If the Signed MOAS Group is verified but no corresponding ROA is found, the Signed MOAS Group is considered suspicious. (3) Invalid: If the Signed MOAS Group cannot be verified, it is considered invalid.

Operational Considerations To aggregate the signatures of all ASes in the AS list, the Signed MOAS Group MUST use BLS Signatures with BLS12-381 elliptic curve . This ensures that the signatures can be efficiently combined into a single global signature. The ASes in the AS List that are authorized by the ROA SHOULD be placed at the beginning of the AS list, ahead of any non-authorized ASes. This ordering can improve the efficiency of the RP's validation process. It is highly RECOMMENDED that the RP only verifies whether the first AS and the prefix can be validated by the ROA. Multiple valid Signed MOAS Group objects can exist that contain the same IP prefix. However, it is highly RECOMMENDED that an AS only participate in one Signed MOAS Group for the same IP prefix. If the AS List of a Signed MOAS Group needs modification, it is highly RECOMMENDED to revoke the current Signed MOAS Group and sign a new one.

Security Considerations Despite it is highly RECOMMENDED that a Signed MOAS Group SHOULD be validated by at least one ROA, the data contained in a Signed MOAS Group is still self-asserted by the group of AS holders. This means that the presence of an AS in the Signed MOAS Group does not inherently imply any authority from the IP prefix holder for the AS to originate a route for any prefixes. Such authority is separately conveyed in the RPKI through a ROA.

IANA Considerations

SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1) IANA is requested to allocate the following in the "SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1)" registry:

Decimal	Description	Reference
TBD	Id-ct-rpkiSignedMoasGroup	draft-li-sidrops-rpki-moasgroup

RPKI Signed Objects IANA is requested to register two OIDs in the "RPKI Signed Objects" registry as follows:

Name	OID	Reference
Signed MoasGroup	1.2.840.113549.1.9.16.1.TBD	draft-li-sidrops-rpki-moasgroup

RPKI Repository Name Schemes IANA is requested to add the Signed MoasGroup file extension to the "RPKI Repository Name Schemes" registry as follows:

Filename Extension	RPKI Object	Reference
.smg	Signed MoasGroup	draft-li-sidrops-rpki-moasgroup

SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0) IANA is requested to allocate the following in the "SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0)" registry:

Decimal	Description	Reference
.TBD	id-mod-rpkiSignedMoasGroup-2024	draft-li-sidrops-rpki-moasgroup

Normative References This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK] 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] 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] To help reduce well-known threats against BGP including prefix mis- announcing and monkey-in-the-middle attacks, one of the security requirements is the ability to validate the origination Autonomous System (AS) of BGP routes. More specifically, one needs to validate that the AS number claiming to originate an address prefix (as derived from the AS_PATH attribute of the BGP route) is in fact authorized by the prefix holder to do so. This document describes a simple validation mechanism to partially satisfy this requirement. [STANDARDS-TRACK] The Border Gateway Protocol (BGP) is the protocol almost exclusively used in the Internet to exchange routing information between network domains. Due to this central nature, it is important to understand the security measures that can and should be deployed to prevent accidental or intentional routing disturbances. This document describes measures to protect the BGP sessions itself such as Time to Live (TTL), the TCP Authentication Option (TCP-AO), and control-plane filtering. It also describes measures to better control the flow of routing information, using prefix filtering and automation of prefix filters, max-prefix filtering, Autonomous System (AS) path filtering, route flap dampening, and BGP community scrubbing. 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] Mattr Self-Issued Consulting This specification defines how to represent cryptographic keys for the pairing-friendly elliptic curves known as Barreto-Lynn-Scott (BLS), for use with the key representation formats of JSON Web Key (JWK) and COSE (COSE_Key). Discussion Venues This note is to be removed before publishing as an RFC. Source for this draft and an issue tracker can be found at https://github.com/tplooker/draft-ietf-cose-bls-key-representations. 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. 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.

Acknowledgments The authors would like to thank Shenglin Jiang, Yangfei Guo, Xingang Shi, Shuhe Wang, Xiaoliang Wang, Hui Wang, and Di Ma.