Internet-Draft RPKI Signed Prefix List January 2024
Snijders & Huston Expires 1 August 2024 [Page]
Intended Status:
Standards Track
J. Snijders
G. Huston

A profile for Signed Prefix Lists for Use in the Resource Public Key Infrastructure (RPKI)


This document defines a "Signed Prefix List", a Cryptographic Message Syntax (CMS) protected content type for use with the Resource Public Key Infrastructure (RPKI) to carry the complete list of prefixes which an Autonomous System (AS) may originate to all or any of its routing peers. The validation of a Signed Prefix List confirms that the holder of the listed ASN produced the object, and that this list is a current, accurate and complete description of address prefixes that may be announced into the routing system originated by this AS.

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

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 1 August 2024.

Table of Contents

1. Introduction

This document defines a "Signed Prefix List", a Cryptographic Message Syntax (CMS) [RFC5652] [RFC6268] protected content type to carry a list of IP address prefixes and an Autonomous System Number. The list of prefixes describes the maximal set of prefixes that the Autonomous System MAY announce to any of its routing peers. The content is signed by the holder of the RPKI private key associated with the listed ASN.

RPKI Signed Prefix Lists allow other RPKI-validating remote routing entities to audit the collection of announcements that have the subject ASN as the originating AS. Any prefixes originated by this AS not contained in a validated Signed Prefix List SHOULD be regarded as ineligible, but ultimately their consequent handling by the local routing entity that performed the audit function is a matter of local policy.

The intent of this object is to offer a RPKI-based successor to the [RFC2622] 'route-set' class objects used in Internet Routing Registries (IRRs). The semantics of the route-set and the Signed Prefix List are similair. The difference is that the RPKI signature allows a relying party of be assured of the currency and authenticity of the Signed Prefix List as a complete enumeration of all prefixes that may be announced as originating by this AS if the object can be validated by the RPKI.

Signed Prefix List objects follow the Signed Object Template for the RPKI [RFC6488].

1.1. 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.

2. The Signed Prefix List ContentType

The eContentType for a Prefix List is defined as id-ct-rpkiSignedPrefixList, with Object Identifier (OID) 1.2.840.113549.

This OID MUST appear within both the eContentType in the encapContentInfo object and the ContentType signed attribute in the signerInfo object (see [RFC6488]).

3. The Signed Prefix List eContent

The content of a Signed Prefix List is a single ASN and a list of IP address prefixes. An Signed Prefix List is formally defined as follows:

  { iso(1) member-body(2) us(840) rsadsi(113549)
    pkcs(1) pkcs9(9) smime(16) mod(0)
    id-mod-rpkiSignedPrefixList-2024(TBD) }


  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) } ;

ct-rpkiSignedPrefixList CONTENT-TYPE ::=
  { TYPE RpkiSignedPrefixList
    IDENTIFIED BY id-ct-rpkiSignedPrefixList }

id-ct-rpkiSignedPrefixList OBJECT IDENTIFIER ::=
  { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
    pkcs-9(9) id-smime(16) id-ct(1) 51 }

RpkiSignedPrefixList ::= SEQUENCE {
  version [0]     INTEGER (0..MAX) DEFAULT 0,
  asID            INTEGER (1..4294967295),
  prefixBlocks    SEQUENCE (SIZE(0..2)) OF AddressFamilyAddressPrefixes }

AddressFamilyAddressPrefixes ::= SEQUENCE {
  addressFamily   ADDRESS-FAMILY.&afi ({AddressFamilySet}),
  addressPrefixes ADDRESS-FAMILY.&Prefixes ({AddressFamilySet}{@addressFamily}) }

  &afi          OCTET STRING (SIZE(2)) UNIQUE,
} WITH SYNTAX { AFI &afi PREFIXES &Prefixes }

AddressFamilySet ADDRESS-FAMILY ::= { addressFamilyIPv4 | addressFamilyIPv6 }

addressFamilyIPv4 ADDRESS-FAMILY ::= { AFI afi-IPv4 PREFIXES IPv4Prefixes }
addressFamilyIPv6 ADDRESS-FAMILY ::= { AFI afi-IPv6 PREFIXES IPv6Prefixes }

afi-IPv4 OCTET STRING ::= '0001'H
afi-IPv6 OCTET STRING ::= '0002'H

IPv4Prefixes ::= SEQUENCE (SIZE(1..MAX)) OF AddressPrefix{ub-IPv4}
IPv6Prefixes ::= SEQUENCE (SIZE(1..MAX)) OF AddressPrefix{ub-IPv6}

ub-IPv4 INTEGER ::= 32
ub-IPv6 INTEGER ::= 128

AddressPrefix {INTEGER: ub} ::= BIT STRING (SIZE(0..ub))


3.1. Version

The version number of the RpkiSignedPrefixList MUST be 0.

3.2. asID

The Autonomous System Number contained here MUST be a contained within the set of AS Identifier resources listed by the EE certificate carried in the CMS certificates field.

3.3. prefixes

This field contains a SEQUENCE of AddressFamilyAddressPrefixes. The AddressFamilyAddressPrefixes elements MUST be ordered in ascending order by numeric value of the addressFamily field.

3.3.1. Element AddressFamilyAddressPrefixes

This field contains a SEQUENCE which contains one instance of addressFamily and one instance of addressPrefixes. addressFamily

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

This field contains a SEQUENCE of parameterized AddressPrefix instances. The canonicalization procedure specified in Section 4.3.3 of [I-D.ietf-sidrops-rfc6482bis] MUST be applied. Element AddressPrefix

This element is length bounded through the Information Object Class ADDRESS-FAMILY. The type is a BIT STRING, see Section of [RFC3779] for more information on encoding IP prefixes.

4. Signed Prefix List Validation

To validate a Signed Prefix List, the RP MUST perform all the validation checks specified in [RFC6488]. 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 3.
  2. The Autonomous System Identifier Delegation extension [RFC3779] MUST be present in the EE certificate contained in the CMS certificates field.
  3. The AS identifier present in the RpkiSignedPrefixList eContent 'asID' field MUST be a subset of the AS Indentifiers present in the certificate extension.
  4. The Autonomous System Identifier Delegation extension MUST NOT contain "inherit" elements.
  5. The IP Address Delegation Extension [RFC3779] is not used in Signed Prefix List, and MUST NOT be present in the EE certificate.

5. Operational Considerations

Multiple valid Signed Prefix List objects which contain the same asID could exist. In such cases the union of address prefix members forms the complete set of members. It is highly RECOMMENDED that a compliant CA maintains a single Signed Prefix List for a given asID.

If an AS holder publishes a Signed Prefix List, then relying parties SHOULD assume that the list is complete for that originating AS, and the presence of any route with the same AS as the originating AS and an address prefix that is not included in the Signed Prefix List implies that the route has been propagated within the routing system without the permission of the originating AS.

The construction of an 'allowlist' for a given EBGP session using Signed Prefix List(s) compliments both best current practises [RFC7454] and the practise of rejecting RPKI-ROV-invalid BGP route announcements [RFC6811]. In other words, if a given BGP route is covered by a Signed Prefix List, but also is "invalid" from a Route Origin Validation perspective, it is RECOMMENDED to reject the route announcement.

5.1. EE Certificates

The Certificate Authority (CA) SHOULD sign only one Signed Prefix List with each generated private key and SHOULD generate a new key pair for each new version of a Signed Prefix List object. The CA MUST generate a new End Entity (EE) certificate for each signing of a particular Signed Prefix List. An associated EE certificate used in this fashion is termed a "one-time-use" EE certificate (see Section 3 of [RFC6487]).

5.2. Object Filenames

A guideline for naming Signed Prefix List objects is that the file name chosen in the repository be a value derived from the public key of the EE certificate. One such method of generating a publication name is described in Section 2.1 of [RFC4387]; convert the 160-bit hash of a EE's public key value into a 27-character string using a modified form of Base64 encoding, with an additional modification as proposed in Section 5, table 2, of [RFC4648].

6. Security Considerations

Relying Parties are warned that the data in a Signed Prefix List is self-asserted by the AS holder. There is no implied authority from any IP prefix holder that grants the AS permission to originate a route for any prefixes. Such an authority is separately conveyed in the RPKI as a ROA.

While a one-time-use EE certificate must only be used to generate and sign a single Signed Prefix List object, CAs are not technically restricted from generating and signing multiple different Signed Prefix List objects with a single key pair. Any Signed Prefix List objects sharing the same EE certificate cannot be revoked individually.

7. IANA Considerations

7.1. SMI Security for S/MIME CMS Content Type (1.2.840.113549.

IANA has temporarily allocated the following in the "SMI Security for S/MIME CMS Content Type (1.2.840.113549." registry:

Table 1
Decimal Description References
51 id-ct-rpkiSignedPrefixList draft-ietf-sidrops-rpki-prefixlist

7.2. RPKI Signed Objects

IANA is requested to register two OIDs in the "RPKI Signed Objects" registry [RFC6488] as follows:

Table 2
Name OID Reference
Signed Prefix List 1.2.840.113549. draft-ietf-sidrops-rpki-prefixlist

7.3. RPKI Repository Name Schemes

IANA is requested to add the Signed Prefix List file extension to the "RPKI Repository Name Schemes" registry [RFC6481] as follows:

Table 3
Filename Extension RPKI Object Reference
.spl Signed Prefix List draft-ietf-sidrops-rpki-prefixlist

7.4. SMI Security for S/MIME Module Identifier (1.2.840.113549.

IANA is requested to allocate the following in the "SMI Security for S/MIME Module Identifier (1.2.840.113549." registry:

Table 4
Decimal Description References
TBD id-mod-rpkiSignedPrefixList-2024 draft-ietf-sidrops-rpki-prefixlist

7.5. Media Types

IANA is requested to register the media type "application/rpki-prefixlist" in the "Media Types" registry as follows:

7.5.1. Signed Prefix List Media Type

Type name:
Subtype name:
Required parameters:
Optional parameters:
Encoding considerations:
Security considerations:
Carries a Signed Prefix List. This media type contains no active content. See Section 4 of draft-ietf-sidrops-rpki-prefixlist for further information.
Interoperability considerations:
Published specification:
Applications that use this media type:
RPKI operators
Fragment identifier considerations:
Additional information:

This media type is a signed object, as defined in [RFC6488], which contains a list of prefixes as defined in draft-ietf-sidrops-rpki-prefixlist.
Magic number(s):
File extension(s):
Macintosh file type code(s):
Person & email address to contact for further information:
Job Snijders (
Intended usage:
Restrictions on usage:
Job Snijders (
Change controller:

8. References

8.1. Normative References

Snijders, J., Maddison, B., Lepinski, M., Kong, D., and S. Kent, "A Profile for Route Origin Authorizations (ROAs)", Work in Progress, Internet-Draft, draft-ietf-sidrops-rfc6482bis-09, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D., Meyer, D., Bates, T., Karrenberg, D., and M. Terpstra, "Routing Policy Specification Language (RPSL)", RFC 2622, DOI 10.17487/RFC2622, , <>.
Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, DOI 10.17487/RFC3779, , <>.
Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, RFC 5652, DOI 10.17487/RFC5652, , <>.
Huston, G., Loomans, R., and G. Michaelson, "A Profile for Resource Certificate Repository Structure", RFC 6481, DOI 10.17487/RFC6481, , <>.
Huston, G., Michaelson, G., and R. Loomans, "A Profile for X.509 PKIX Resource Certificates", RFC 6487, DOI 10.17487/RFC6487, , <>.
Lepinski, M., Chi, A., and S. Kent, "Signed Object Template for the Resource Public Key Infrastructure (RPKI)", RFC 6488, DOI 10.17487/RFC6488, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.

8.2. Informative References

Gutmann, P., Ed., "Internet X.509 Public Key Infrastructure Operational Protocols: Certificate Store Access via HTTP", RFC 4387, DOI 10.17487/RFC4387, , <>.
Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, , <>.
Schaad, J. and S. Turner, "Additional New ASN.1 Modules for the Cryptographic Message Syntax (CMS) and the Public Key Infrastructure Using X.509 (PKIX)", RFC 6268, DOI 10.17487/RFC6268, , <>.
Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. Austein, "BGP Prefix Origin Validation", RFC 6811, DOI 10.17487/RFC6811, , <>.
Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, , <>.

Appendix A. Acknowledgements

The authors wish to thank Russ Housley for feedback.

Appendix B. Example payloads

B.1. Example Signed Prefix List eContent Payload

Below an example of a DER-encoded Signed Prefix List eContent is provided with annotation following the '#' character.

$ cat << EOF | xxd -r -ps | openssl asn1parse -inform DER -i -dump
    0:d=0  hl=3 l= 177 cons: SEQUENCE
    3:d=1  hl=2 l=   2 prim:  INTEGER       :3CCA  # AS 15562
    7:d=1  hl=3 l= 170 cons:  SEQUENCE
   10:d=2  hl=2 l= 115 cons:   SEQUENCE
   12:d=3  hl=2 l=   2 prim:    OCTET STRING
      0000 - 00 01                                 # AFI IPv4
   16:d=3  hl=2 l= 109 cons:    SEQUENCE
   18:d=4  hl=2 l=   4 prim:     BIT STRING
      0000 - 00 43 dd f5                           #
   24:d=4  hl=2 l=   4 prim:     BIT STRING
      0000 - 00 a5 fe e1                           #
   30:d=4  hl=2 l=   5 prim:     BIT STRING
      0000 - 06 a5 fe ff                           #
      0005 - <SPACES/NULS>
... snip ...
  127:d=2  hl=2 l=  51 cons:   SEQUENCE
  129:d=3  hl=2 l=   2 prim:    OCTET STRING
      0000 - 00 02                                 # AFI IPv6
  133:d=3  hl=2 l=  45 cons:    SEQUENCE
  135:d=4  hl=2 l=   7 prim:     BIT STRING
      0000 - 01 20 01 04 18 14 4e                  # 2001:418:144e::/47
  144:d=4  hl=2 l=   7 prim:     BIT STRING
      0000 - 00 20 01 06 7c 20 8c                  # 2001:67c:208c::/48
... snip ...

Authors' Addresses

Job Snijders
Geoff Huston
6 Cordelia St
South Brisbane QLD 4101