Fastly

Amsterdam Netherlands job@fastly.com

Asia Pacific Network Information Centre

6 Cordelia St South Brisbane 4101 Australia QLD tomh@apnic.net

Workonline Communications

Cape Town South Africa benm@workonline.africa

ops sidrops security cryptography X.509 This document defines a Cryptographic Message Syntax (CMS) protected content type for use with the Resource Public Key Infrastructure (RPKI) to carry a general-purpose listing of checksums (a 'checklist'). The objective is to allow for the creation of an attestation, termed an "RPKI Signed Checklist (RSC)", which contains one or more checksums of arbitrary digital objects (files) that are signed with a specific set of Internet Number Resources. When validated, an RSC confirms that the respective Internet resource holder produced the RSC.

Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .

Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents () in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.

Table of Contents

• .  Introduction
  • .  Requirements Language
• .  RSC Profile and Distribution
  • .  RSC EE Certificates
• .  The RSC eContentType
• .  The RSC eContent
  • .  Version
  • .  Resources
    • .  ConstrainedASIdentifiers Type
    • .  ConstrainedIPAddrBlocks Type
  • .  digestAlgorithm
  • .  checkList
    • .  FileNameAndHash
• .  RSC Validation
• .  Verifying Files or Data Using RSC
• .  Operational Considerations
• .  Security Considerations
• .  IANA Considerations
  • .  SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1)
  • .  RPKI Signed Objects
  • .  RPKI Repository Name Schemes
  • .  SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0)
  • .  Media Types
• . References
  • .  Normative References
  • .  Informative References
• Acknowledgements
• Authors' Addresses

Introduction This document defines a Cryptographic Message Syntax (CMS) protected content type for a general-purpose listing of checksums (a 'checklist'), for use with the Resource Public Key Infrastructure (RPKI) . The CMS protected content type is intended to provide for the creation and validation of an RPKI Signed Checklist (RSC), a checksum listing signed with a specific set of Internet Number Resources. The objective is to allow for the creation of an attestation that, when validated, provides a means to confirm a given Internet resource holder produced the RSC. RPKI Signed Checklists are expected to facilitate inter-domain business use cases that depend on an ability to verify resource holdership. RPKI-based validation processes are expected to become the industry norm for automated Bring Your Own IP (BYOIP) on-boarding or establishment of physical interconnections between Autonomous Systems (ASes). The RSC concept borrows heavily from Resource Tagged Attestation (RTA) , Manifests , and OpenBSD's signify utility . The main difference between an RSC and RTA is that the RTA profile allows multiple signers to attest a single digital object through a checksum of its content, while the RSC profile allows a single signer to attest the content of multiple digital objects. A single signer profile is considered a simplification for both implementers and operators.

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.

RSC Profile and Distribution RSC follows the Signed Object Template for the RPKI with one exception: because RSCs MUST NOT be distributed through the global RPKI repository system, the Subject Information Access (SIA) extension MUST be omitted from the RSC's X.509 End-Entity (EE) certificate. What constitutes suitable transport for RSC files is deliberately unspecified. For example, it might be a USB stick, a web interface secured with HTTPS, an email signed with Pretty Good Privacy (PGP), a T-shirt printed with a QR code, or a carrier pigeon.

RSC EE Certificates The Certification Authority (CA) MUST only sign one RSC with each EE certificate and MUST generate a new key pair for each new RSC. This type of EE certificate is termed a "one-time-use" EE certificate (see ).

The RSC eContentType The eContentType for an RSC is defined as id-ct-signedChecklist, with Object Identifier (OID) 1.2.840.113549.1.9.16.1.48. This OID MUST appear within both the eContentType in the encapContentInfo object and the ContentType signed attribute in the signerInfo object (see ).

The RSC eContent The content of an RSC indicates that a checklist for arbitrary digital objects has been signed with a specific set of Internet Number Resources. An RSC is formally defined as follows: RpkiSignedChecklist-2022 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) mod(0) id-mod-rpkiSignedChecklist-2022(73) } DEFINITIONS EXPLICIT TAGS ::= BEGIN IMPORTS CONTENT-TYPE, Digest, DigestAlgorithmIdentifier FROM CryptographicMessageSyntax-2010 -- in [RFC6268] { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) modules(0) id-mod-cms-2009(58) } IPAddressOrRange, ASIdOrRange FROM IPAddrAndASCertExtn -- in [RFC3779] { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) mod(0) id-mod-ip-addr-and-as-ident(30) } ; ct-rpkiSignedChecklist CONTENT-TYPE ::= { TYPE RpkiSignedChecklist IDENTIFIED BY id-ct-signedChecklist } id-ct-signedChecklist OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) id-smime(16) id-ct(1) 48 } RpkiSignedChecklist ::= SEQUENCE { version [0] INTEGER DEFAULT 0, resources ResourceBlock, digestAlgorithm DigestAlgorithmIdentifier, checkList SEQUENCE (SIZE(1..MAX)) OF FileNameAndHash } FileNameAndHash ::= SEQUENCE { fileName PortableFilename OPTIONAL, hash Digest } PortableFilename ::= IA5String (FROM("a".."z" | "A".."Z" | "0".."9" | "." | "_" | "-")) ResourceBlock ::= SEQUENCE { asID [0] ConstrainedASIdentifiers OPTIONAL, ipAddrBlocks [1] ConstrainedIPAddrBlocks OPTIONAL } -- at least one of asID or ipAddrBlocks MUST be present ( WITH COMPONENTS { ..., asID PRESENT} | WITH COMPONENTS { ..., ipAddrBlocks PRESENT } ) ConstrainedIPAddrBlocks ::= SEQUENCE (SIZE(1..MAX)) OF ConstrainedIPAddressFamily ConstrainedIPAddressFamily ::= SEQUENCE { addressFamily OCTET STRING (SIZE(2)), addressesOrRanges SEQUENCE (SIZE(1..MAX)) OF IPAddressOrRange } ConstrainedASIdentifiers ::= SEQUENCE { asnum [0] SEQUENCE (SIZE(1..MAX)) OF ASIdOrRange } END

Version The version number of the RpkiSignedChecklist MUST be 0.

Resources The resources contained here are the resources used to mark the attestation and MUST be a subset of the set of resources listed by the EE certificate carried in the CMS certificates field. If the asID field is present, it MUST contain an instance of ConstrainedASIdentifiers. If the ipAddrBlocks field is present, it MUST contain an instance of ConstrainedIPAddrBlocks. At least one of asID or ipAddrBlocks MUST be present. ConstrainedASIdentifiers and ConstrainedIPAddrBlocks are specified such that the resulting DER-encoded data instances are binary compatible with ASIdentifiers and IPAddrBlocks (defined in ), respectively. Implementations encountering decoding errors whilst attempting to read DER-encoded data using this specification should be aware of the possibility that the data may have been encoded using an implementation intended for use with . Such data may contain elements prohibited by the current specification. Attempting to decode the errored data using the more permissive specification contained in may enable implementors to gather additional context for use when reporting errors to the user. However, implementations MUST NOT ignore errors resulting from the more restrictive definitions contained herein; in particular, such errors MUST cause the validation procedure described in to fail.

ConstrainedASIdentifiers Type ConstrainedASIdentifiers is a SEQUENCE consisting of a single field, asnum, which in turn contains a SEQUENCE OF one or more ASIdOrRange instances as defined in . ConstrainedASIdentifiers is defined such that the resulting DER-encoded data are binary compatible with ASIdentifiers defined in .

ConstrainedIPAddrBlocks Type ConstrainedIPAddrBlocks is a SEQUENCE OF one or more instances of ConstrainedIPAddressFamily. There MUST be only one instance of ConstrainedIPAddressFamily per unique Address Family Identifier (AFI). The elements of ConstrainedIPAddressFamily MUST be ordered by ascending addressFamily values (treating the octets as unsigned numbers). Thus, when both IPv4 and IPv6 addresses are specified, the IPv4 addresses MUST precede the IPv6 addresses (since the IPv4 AFI of 0001 is less than the IPv6 AFI of 0002). ConstrainedIPAddrBlocks is defined such that the resulting DER-encoded data are binary compatible with IPAddrBlocks defined in .

ConstrainedIPAddressFamily Type

addressFamily Field The addressFamily field is an OCTET STRING containing a 2-octet AFI, in network byte order. Unlike IPAddrBlocks , a third octet containing a Subsequent Address Family Identifier (SAFI) MUST NOT be present. AFIs are specified in the "Address Family Numbers" registry maintained by IANA.

addressesOrRanges Field The addressesOrRanges element is a SEQUENCE OF one or more IPAddressOrRange values, as defined in . The rules for canonicalization and encoding defined in apply to the value of addressesOrRanges.

digestAlgorithm The digest algorithm is used to create the message digest of the attested digital object(s). This algorithm MUST be a hashing algorithm defined in .

checkList This field is a SEQUENCE OF one or more FileNameAndHash values. There is one FileNameAndHash entry for each digital object referenced on the RSC.

FileNameAndHash Each FileNameAndHash is an ordered pair of the name of the directory entry containing the digital object and the message digest of the digital object. The hash field is mandatory. The value of the hash field is the calculated message digest of the digital object. The hashing algorithm is specified in the digestAlgorithm field. The fileName field is OPTIONAL. This is to allow RSCs to be used in a "stand-alone" fashion in which nameless digital objects are addressed directly through their respective message digest rather than through a file system abstraction. If the fileName field is present, then its value:

• MUST contain only characters specified in the Portable Filename Character Set as defined in .
• MUST be unique with respect to the other FileNameAndHash elements of checkList for which the fileName field is also present.

Conversely, if the fileName field is omitted, then the value of the hash field MUST be unique with respect to the other FileNameAndHash elements of checkList for which the fileName field is also omitted.

RSC Validation Before a Relying Party (RP) can use an RSC to validate a set of digital objects, the RP MUST first validate the RSC. To validate an RSC, the RP MUST perform all the validation checks specified in , except for checking for the presence of an SIA extension, which MUST NOT be present in the EE certificate (see ). In addition, the RP MUST perform the following RSC-specific validation steps:

1. The contents of the CMS eContent field MUST conform to all of the constraints described in , including the constraints described in .
2. If the asID field is present within the contents of the resources field, then the AS identifier delegation extension MUST be present in the EE certificate contained in the CMS certificates field. The AS identifiers present in the eContent resources field MUST be a subset of those present in the certificate extension. The EE certificate's AS identifier delegation extension MUST NOT contain "inherit" elements.
3. If the ipAddrBlocks field is present within the contents of the resources field, then the IP address delegation extension MUST be present in the EE certificate contained in the CMS certificates field. The IP addresses present in the eContent resources field MUST be a subset of those present in the certificate extension. The EE certificate's IP address delegation extension MUST NOT contain "inherit" elements.

Verifying Files or Data Using RSC To verify a set of digital objects with an RSC:

• The RSC MUST be validated according to the procedure described in . If the RSC cannot be validated, verification MUST fail. This error SHOULD be reported to the user.
• For every digital object to be verified:
  1. If the verification procedure is provided with a filename for the object being verified (e.g., because the user has provided a file system path from which to read the object), then verification SHOULD proceed in "filename-aware" mode. Otherwise, verification SHOULD proceed in "filename-unaware" mode. Implementations MAY provide an option to override the verification mode, for example, to ignore the fact that the object is to be read from a file.
  2. The message digest MUST be computed from the file contents or data using the digest algorithm specified in the digestAlgorithm field of the RSC.
  3. The digest computed in Step MUST be compared to the value appearing in the hash field of all FileNameAndHash elements of the checkList field of the RSC. One or more FileNameAndHash elements MUST be found with a matching hash value; otherwise, verification MUST fail, and the error SHOULD be reported to the user.
  4. If the mode selected in Step is "filename-aware", then exactly one of the FileNameAndHash elements matched in Step MUST contain a fileName field value exactly matching the filename of the object being verified. Alternatively, if the mode selected in Step is "filename-unaware", then exactly one of the FileNameAndHash elements matched in Step MUST have the fileName field omitted. Otherwise, verification MUST fail, and the error SHOULD be reported to the user.

Note that in the above procedure, not all elements of checkList necessarily need be used. That is, it is not an error if the length of checkList is greater than the size of the set of digital objects to be verified. However, in this situation, implementations SHOULD issue a warning to the user, allowing for corrective action to be taken if necessary.

Operational Considerations When creating digital objects of a plain-text nature (such as ASCII, UTF-8, HTML, Javascript, and XML), converting such objects into a lossless compressed form is RECOMMENDED. Distributing plain-text objects within a compression envelope (such as GZIP ) might help avoid unexpected canonicalization at intermediate systems (which in turn would lead to checksum verification errors). Validator implementations are expected to treat a checksummed digital object as a string of arbitrary single octets. If a fileName field is present, but no digital object within the set of to-be-verified digital objects has a filename that matches the content of that field, a validator implementation SHOULD compare the message digest of each digital object to the value from the hash field of the associated FileNameAndHash and report matches to the user for further consideration.

Security Considerations RPs are hereby warned that the data in an RSC is self-asserted. When determining the meaning of any data contained in an RSC, RPs MUST NOT make any assumptions about the signer beyond the fact that it had sufficient control of the issuing CA to create the object. These data have not been verified by the Certificate Authority (CA) that issued the CA certificate to the entity that issued the EE certificate used to validate the RSC. RPKI certificates are not bound to real-world identities; see for an elaboration. RPs can only associate real-world entities to Internet Number Resources by additionally consulting an exogenous authority. RSCs are a tool to communicate assertions signed with Internet Number Resources and do not communicate any other aspect of the resource holder's business operations, such as the identity of the resource holder itself. RSC objects are not distributed through the RPKI repository system. From this, it follows that third parties who do not have a copy of a given RSC may not be aware of the existence of that RSC. Since RSC objects use EE certificates but all other currently defined types of RPKI object profiles are published in public CA repositories, an observer may infer from discrepancies in the repository that RSC object(s) may exist. For example, if a CA does not use random serial numbers for certificates, an observer could detect gaps between the serial numbers of the published EE certificates. Similarly, if the CA includes a serial number on a Certificate Revocation List (CRL) that does not match any published object, an observer could postulate that an RSC EE certificate was revoked. Conversely, a gap in serial numbers does not imply that an RSC exists. Nor does the presence in a CRL of a serial number unknown to the RP imply an RSC object exists: the implicitly referenced object might not be an RSC, it might have never been published, or it may have been revoked before it was visible to RPs. In general, it is not possible to confidently infer the existence or non-existence of RSCs from the repository state without access to a given RSC. While a one-time-use EE certificate must only be used to generate and sign a single RSC object, CAs technically are not restricted from generating and signing multiple different RSC objects with a single key pair. Any RSC objects sharing the same EE certificate cannot be revoked individually.

IANA Considerations

SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1) IANA has allocated the following in the "SMI Security for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1)" registry:

Decimal	Description	References
48	id-ct-signedChecklist	RFC 9323

RPKI Signed Objects IANA has registered the OID for the RSC in the "RPKI Signed Objects" registry as follows:

Name	OID	Reference
Signed Checklist	1.2.840.113549.1.9.16.1.48	RFC 9323

RPKI Repository Name Schemes IANA has added the Signed Checklist file extension to the "RPKI Repository Name Schemes" registry as follows:

Filename Extension	RPKI Object	Reference
.sig	Signed Checklist	RFC 9323

SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0) IANA has allocated the following in the "SMI Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0)" registry:

Decimal	Description	References
73	id-mod-rpkiSignedChecklist-2022	RFC 9323

Media Types IANA has registered the media type "application/rpki-checklist" in the "Media Types" registry as follows:

Type name:

application

Subtype name:

rpki-checklist

Required parameters:

N/A

Optional parameters:

N/A

Encoding considerations:

binary

Security considerations:

Carries an RPKI Signed Checklist. This media type contains no active content. See of RFC 9323 for further information.

Interoperability considerations:

N/A

Published specification:

RFC 9323

Applications that use this media type:

RPKI operators

Fragment identifier considerations:

N/A

Additional information:

Content:

This media type is a signed object, as defined in [RFC6488], which contains a payload of a list of checksums as defined in RFC 9323.

Magic number(s):

N/A

File extension(s):

.sig

Macintosh file type code(s):

N/A

Person & email address to contact for further information:

Job Snijders (job@fastly.com)

Intended usage:

COMMON

Restrictions on usage:

N/A

Author:

Job Snijders (job@fastly.com)

Change controller:

IETF

References Normative References IEEE and The Open Group Issue 7 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. 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] 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 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] This document defines a standard profile for X.509 certificates for the purpose of supporting validation of assertions of "right-of-use" of Internet Number Resources (INRs). The certificates issued under this profile are used to convey the issuer's authorization of the subject to be regarded as the current holder of a "right-of-use" of the INRs that are described in the certificate. This document contains the normative specification of Certificate and Certificate Revocation List (CRL) syntax in the Resource Public Key Infrastructure (RPKI). This document also specifies profiles for the format of certificate requests and specifies the Relying Party RPKI certificate path validation procedure. [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 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 (CRLs), Cryptographic Message Syntax (CMS) signed objects and certification requests as well as for the relying parties (RPs) that verify these digital signatures. 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. This document defines a "manifest" for use in the Resource Public Key Infrastructure (RPKI). A manifest is a signed object (file) that contains a listing of all the signed objects (files) in the repository publication point (directory) associated with an authority responsible for publishing in the repository. For each certificate, Certificate Revocation List (CRL), or other type of signed objects issued by the authority that are published at this repository publication point, the manifest contains both the name of the file containing the object and a hash of the file content. Manifests are intended to enable a relying party (RP) to detect certain forms of attacks against a repository. Specifically, if an RP checks a manifest's contents against the signed objects retrieved from a repository publication point, then the RP can detect replay attacks, and unauthorized in-flight modification or deletion of signed objects. This document obsoletes RFC 6486. Informative References Internet Assigned Numbers Authority This specification defines a lossless compressed data format that is compatible with the widely used GZIP utility. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. The Cryptographic Message Syntax (CMS) format, and many associated formats, are expressed using ASN.1. The current ASN.1 modules conform to the 1988 version of ASN.1. This document updates some auxiliary ASN.1 modules to conform to the 2008 version of ASN.1; the 1988 ASN.1 modules remain the normative version. There are no bits- on-the-wire changes to any of the formats; this is simply a change to the syntax. This document is not an Internet Standards Track specification; it is published for informational purposes. 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. There is a false notion that Internet Number Resources (INRs) in the RPKI can be associated with the real-world identity of the 'holder' of an INR. This document specifies that RPKI does not associate to the INR holder. Asia Pacific Network Information Centre Asia Pacific Network Information Centre Asia Pacific Network Information Centre NLNet Labs B.V. NLNet Labs B.V. Work in Progress

Acknowledgements The authors wish to thank , , , , , , , and for prior art. The authors thank for reviewing the ASN.1 notation and providing suggestions. The authors would like to thank , , , , , , , , , , , , , , and for document review and suggestions.

Authors' Addresses Fastly

Amsterdam Netherlands job@fastly.com

Asia Pacific Network Information Centre

6 Cordelia St South Brisbane 4101 Australia QLD tomh@apnic.net

Workonline Communications

Cape Town South Africa benm@workonline.africa