Network Working Group                                       S. Josefsson
Internet-Draft                                                    SJD AB
Intended status: Informational                            March 20, 2016
Expires: September 21, 2016

                 Using Curve25519 and Curve448 in PKIX


   This document specify "named curve" object identifiers for the
   Curve25519 and Curve448 curves, for use in various X.509 PKIX

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   This Internet-Draft will expire on September 21, 2016.

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1.  Introduction

   In [RFC7748], the elliptic curves Curve25519 and Curve448 are
   described.  They are designed with performance and security in mind.
   The curves may be used for Diffie-Hellman and Digital Signature

   This RFC define ASN.1 "named curve" object identifiers for Curve25519
   and Curve448, for use in the Internet X.509 PKI [RFC5280].

   Rather than defining a new subject public key format for these two
   curves, this document re-use the existing ECDSA/ECDH public-key
   contained (described in section 2.3.5 of [RFC3279]) and introduce two
   new "named curve" OIDs.  This approach is the same as for the
   Brainpool curves [RFC5639].

2.  Requirements Terminology

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

3.  Curve25519 and Curve448 Named Curve Identifier

   Certificates conforming to [RFC5280] may convey a public key for any
   public key algorithm.  The certificate indicates the algorithm
   through an algorithm identifier.  This algorithm identifier is an OID
   and optionally associated parameters.  Section 2.3.5 of [RFC3279]
   describe ECDSA/ECDH public keys, specifying the id-ecPublicKey OID.
   This OID has the associated EcpkParameters parameters structure,
   which contains the namedCurve CHOICE.  Here we introduce two new OIDs
   for use in the namedCurve field.

       id-Curve25519   OBJECT IDENTIFIER ::= { }
       id-Curve448     OBJECT IDENTIFIER ::= { }
       id-Curve25519ph OBJECT IDENTIFIER ::= { }
       id-Curve448ph   OBJECT IDENTIFIER ::= { }

   The OID id-Curve25519 refers to Curve25519.  The OID id-Curve448
   refers to Curve448.  Both curves are described in [RFC7748].  The
   OIDs id-Curve25519ph and id-Curve448ph refers to Curve25519 and
   Curve448 when used with pre-hashing as Ed25519ph and Ed448ph
   described in [I-D.irtf-cfrg-eddsa].

   The public key value encoded into the ECPoint value is the raw binary
   values described in [RFC7748].

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4.  Acknowledgements

   Text and/or inspiration were drawn from [RFC5280], [RFC3279],
   [RFC5480], and [RFC5639].

   Several people suggested the utility of specifying OIDs for encoding
   Curve25519/Curve448 public keys into PKIX certificates, the editor of
   this document cannot take credit for this idea.

5.  IANA Considerations


6.  Security Considerations

   The security considerations of [RFC3279], [RFC5280], [RFC5480] and
   [RFC7748] apply accordingly.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3279]  Bassham, L., Polk, W., and R. Housley, "Algorithms and
              Identifiers for the Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 3279, April 2002.

   [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.

   [RFC5480]  Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
              "Elliptic Curve Cryptography Subject Public Key
              Information", RFC 5480, March 2009.

   [RFC7748]  Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
              for Security", RFC 7748, DOI 10.17487/RFC7748, January
              2016, <>.

              Josefsson, S. and I. Liusvaara, "Edwards-curve Digital
              Signature Algorithm (EdDSA)", draft-irtf-cfrg-eddsa-00
              (work in progress), October 2015.

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7.2.  Informative References

   [RFC5639]  Lochter, M. and J. Merkle, "Elliptic Curve Cryptography
              (ECC) Brainpool Standard Curves and Curve Generation", RFC
              5639, March 2010.

Author's Address

   Simon Josefsson


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