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The Profile for Algorithms and Key Sizes for Use in the Resource Public Key Infrastructure (RPKI)

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 6485.
Author Geoff Huston
Last updated 2020-01-21 (Latest revision 2011-04-13)
Replaces draft-huston-sidr-rpki-algs
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Additional resources Mailing list discussion
Stream WG state WG Document
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IESG IESG state Became RFC 6485 (Proposed Standard)
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Responsible AD Stewart Bryant
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SIDR                                                           G. Huston
Internet-Draft                                                     APNIC
Intended status: Standards Track                          April 13, 2011
Expires: October 15, 2011

The Profile for Algorithms and Key Sizes for use in the Resource Public
                           Key Infrastructure


   This document specifies the algorithms, algorithms' parameters,
   asymmetric key formats, asymmetric key size and signature format for
   the Resource Public Key Infrastructure 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.

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 October 15, 2011.

Copyright Notice

   Copyright (c) 2011 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 Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   This document specifies:

      *  the digital signature algorithm and parameters;
      *  the hash algorithm and parameters;
      *  the public and private key formats; and,
      *  the signature format
   used by Resource Public Key Infrastructure (RPKI) subscribers when
   they apply digital signatures to certificates, Certificate Revocation
   Lists (CRLs), and signed objects (e.g., Route Origin Authorizations
   (ROAs) and manifests).  Relying Parties (RPs) also use this document
   when verify RPKI subscribers' digital signatures [ID.ietf-sidr-arch].

   This document is referenced by other RPKI profiles and
   specifications, including the RPKI Certificate Policy (CP)
   [ID.ietf-sidr-cp], the RPKI Certificate Profile
   [ID.ietf-sidr-res-certs], the SIDR architecture [ID.ietf-sidr-arch],
   and the signed object template for the RPKI
   [ID.ietf-sidr-signed-object].  Familiarity with these documents is

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC2119.

2.  Algorithms

   Two cryptographic algorithms are used in the RPKI:

      *  The signature algorithm used in certificates, CRLs, and signed
         objects is RSA Public-Key Cryptography Standards (PKCS) #1
         Version 1.5 (sometimes referred to as "RSASSA-PKCS1-v1_5") from
         Section 5 of [RFC4055].

      *  The hashing algorithm used in certificates, CRLs, and signed
         objects is SHA-256 [SHS].  Hash algorithms are not identified
         by themselves in certificates and CRLs instead they are
         combined with the digital signature algorithm (see below).
         When used in the Cryptographic Message Syntax (CMS) SignedData,
         the hash algorithm (in this case, the hash algorithm is

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         sometimes called a message digest algorithm) is identified by
         itself.  For CMS SignedData, the object identifier and
         parameters for SHA-256 in [RFC5754] MUST be used when
         populating the digestAlgorithms and digestAlgorithm fields.

         NOTE: The exception to the above hashing algorithm is the use
         of SHA-1 [SHS] when CAs generate authority and subject key
         identifiers [ID.ietf-sidr-res-certs].

   When used to generate and verify digital signatures the hash and
   digital signature algorithms are referred together, i.e., "RSA PKCS#1
   v1.5 with SHA-256" or more simply "RSA with SHA-256".  The Object
   Identifier (OID) sha256withRSAEncryption from [RFC4055] MUST be used.

   Locations for this OID are as follows:

      In the certificate, the OID appears in the signature and
      signatureAlgorithm fields [RFC4055];
      In the CRL, the OID appears in the signatureAlgorithm field
      In CMS SignedData, the OID appears in each SignerInfo
      signatureAlgoithm field [RFC3370] using the OID from above; and,
      In a certification request, the OID appears in the PKCS #10
      signatureAlgorithm field [RFC2986], or in the Certificate Request
      Message Format (CRMF) POPOSigningKey signature field [RFC4211].

3.  Asymmetric Key Pair Formats

   The RSA key pairs used to compute the signatures MUST have a 2048-bit
   modulus and a public exponent (e) of 65,537.

3.1.  Public Key Format

   The Subject's public key is included in subjectPublicKeyInfo
   [RFC5280].  It has two sub-fields: algorithm and subjectPublicKey.
   The values for the structures and their sub-structures follow:

   algorithm (which is an AlgorithmIdentifier type):
      The object identifier for RSA PKCS#1 v1.5 with SHA-256 MUST be
      used in the algorithm field, as specified in Section 5 of
      [RFC4055].  The value for the associated parameters from that
      clause MUST also be used for the parameters field.

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      RSAPublicKey MUST be used to encode the certificate's
      subjectPublicKey field, as specified in [RFC4055].

3.2.  Private Key Format

   Local Policy determines private key format.

4.  Signature Format

   The structure for the certificate's signature field is as specified
   in Section 1.2 of [RFC4055].  The structure for the Cryptographic
   Message Syntax (CMS) SignedData's signature field is as specified in

5.  Additional Requirements

   It is anticipated that the RPKI will require the adoption of updated
   key sizes and a different set of signature and hash algorithms over
   time, in order to maintain an acceptable level of cryptographic
   security to protect the integrity of signed products in the RPKI.
   This profile should be relaced to specify such future requirements,
   as and when appropriate.

   CAs and RPs SHOULD be capable of supporting a transition to allow for
   the phased introduction of additional encryption algorithms and key
   specifications, and also accommodate the orderly deprecation of
   previously specified algorithms and keys.  Accordingly, CAs and RPs
   SHOULD be capable of supporting multiple RPKI algorithm and key
   profiles simultaneously within the scope of such anticipated
   transitions.  The recommended procedures to implement such a
   transition of key sizes and algorithms is not specified in this

6.  Security Considerations

   The Security Considerations of [RFC4055], [RFC5280], and
   [ID.ietf-sidr-res-certs] a apply to certificate and CRLs.  The
   Security Considerations of [RFC5754] apply to signed objects.  No new
   security are introduced as a result of this specification.

7.  IANA Considerations

   [There are no IANA considerations in this document.]

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8.  Acknowledgments

   The author acknowledges the re-use in this draft of material
   originally contained in working drafts the RPKI Certificate Policy
   and Resource Certificate profile documents.  The co-authors of these
   two documents, namely Stephen Kent, Derrick Kong, Karen Seo, Ronald
   Watro, George Michaelson and Robert Loomans, are acknowledged, with
   thanks.  The constraint on key size noted in this profile is the
   outcome of comments from Stephen Kent and review comments from David
   Cooper.  Sean Turner has provided additional review input to this

9.  Normative References

              Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", draft-ietf-sidr-arch (work in
              progress), September 2010.

              Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate
              Policy (CP) for the Resource PKI (RPKI)",
              draft-ietf-sidr-cp (work in progress), September 2010.

              Husotn, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates",
              draft-ietf-sidr-res-certs (work in progress), May 2008.

              Lepinski, M., Chi, A., and S. Kent, "Signed Object
              Template for the Resource Public Key Infrastructure",
              draft-ietf-sidr-signed-object-01.txt (work in progress),
              October 2010.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              November 2000.

   [RFC3370]  Housley, R., "Cryptographic Message Syntax (CMS)
              Algorithms", RFC 3370, August 2002.

   [RFC4055]  Schaad, J., Kaliski, B., and R. Housley, "Additional
              Algorithms and Identifiers for RSA Cryptography for use in
              the Internet X.509 Public Key Infrastructure Certificate
              and Certificate Revocation List (CRL) Profile", RFC 4055,
              June 2005.

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   [RFC4211]  Schaad, J., "Internet X.509 Public Key Infrastructure
              Certificate Request Message Format (CRMF)", RFC 4211,
              September 2005.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC5754]  Turner, S., "Using SHA2 Algorithms with Cryptographic
              Message Syntax", RFC 5754, January 2010.

   [SHS]      National Institute of Standards and Technology (NIST),
              "FIPS Publication 180-3: Secure Hash Standard", FIPS
              Publication 180-3, October 2008.

Author's Address

   Geoff Huston


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