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Versions: (draft-nir-ipsecme-eddsa) 00 01 02 03

IPSecME Working Group                                             Y. Nir
Internet-Draft                                               Check Point
Intended status: Standards Track                          April 15, 2017
Expires: October 17, 2017


Using Edwards-curve Digital Signature Algorithm (EdDSA) in the Internet
                          Key Exchange (IKEv2)
                      draft-ietf-ipsecme-eddsa-03

Abstract

   This document describes the use of the Edwards-curve digital
   signature algorithm in the IKEv2 protocol.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   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 17, 2017.

Copyright Notice

   Copyright (c) 2017 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
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   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
   2.  The "Identity" Hash Identifier  . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Appendix A.  ASN.1 Objects  . . . . . . . . . . . . . . . . . . .   5
     A.1.  ASN.1 Object for Ed25519  . . . . . . . . . . . . . . . .   5
     A.2.  ASN.1 Object for Ed448  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The Internet Key Exchange protocol [RFC7296] can use arbitrary
   signature algorithms as described in [RFC7427].  The latter RFC
   defines the SIGNATURE_HASH_ALGORITHMS notification where each side of
   the IKE negotiation lists its supported hash algorithms.  This
   assumes that all signature schemes involve a hashing phase followed
   by a signature phase.  This made sense because most signature
   algorithms either cannot sign messages bigger than their key or
   truncate messages bigger than their key.

   EdDSA ([RFC8032]) defines signature methods that do not require pre-
   hashing of the message.  Unlike other methods, these accept
   arbitrary-sized messages, so no pre-hashing is required.  These
   methods are called Ed25519 and Ed448, which respectively use the
   Edwards 25519 and the Edwards 448 ("Goldilocks") curves.  Although
   that document also defines pre-hashed versions of these algorithm,
   those versions are not recommended for protocols where the entire to-
   be-signed message is available at once.  See section 8.5 or RFC 8032
   for that recommendation.

   EdDSA defines the binary format of the signatures that should be used
   in the "Signature Value" field of the Authentication Data Format in
   section 3.  The CURDLE PKIX document ([I.D-curdle-pkix]) defines the
   object identifiers (OIDs) for these signature methods.  For
   convenience, these OIDs are repeated in Appendix A.

   In order to signal within IKE that no hashing needs to be done, we
   define a new value has in the SIGNATURE_HASH_ALGORITHMS notification,
   one that indicates that no hashing is performed.








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1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  The "Identity" Hash Identifier

   This document defines a new value called "Identity" (value is 5) in
   the hash algorithm registry for use in the SIGNATURE_HASH_ALGORITHMS
   notification.  Inserting this new value into the notification
   indicates that the receiver supports at least one signature algorithm
   that accepts arbitrary-sized messages such as Ed25519 and Ed448.

   Ed25519 and Ed448 are only defined with the Identity hash, and MUST
   NOT be sent to a receiver that has not indicated support for the
   "Identity" hash.

   The pre-hashed versions of Ed25519 and Ed448 (Ed25519ph and Ed448ph
   respectively) SHOULD NOT be used in IKE.

3.  Security Considerations

   The new "Identity" value is needed only for signature algorithms that
   accept an arbitrary-sized input.  It MUST NOT be used if none of the
   supported and configured algorithms have this property.  On the other
   hand there is no good reason to pre-hash the inputs where the
   signature algorithm has that property.  For this reason
   implementations MUST have the "Identity" value in the
   SIGNATURE_HASH_ALGORITHMS notification when EdDSA is supported and
   configured.  Implementations SHOULD NOT have other hash algorithms in
   the notification if all supported and configured signature algorithms
   have this property.

4.  IANA Considerations

   IANA has assigned the value 5 for the algorithm with the name
   "Identity" in the "IKEv2 Hash Algorithms" registry with this draft as
   reference.

   Upon publication of this document IANA is requested to update the
   entry with this document as reference.

5.  Normative References







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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <http://www.rfc-editor.org/info/rfc7296>.

   [RFC7427]  Kivinen, T. and J. Snyder, "Signature Authentication in
              the Internet Key Exchange Version 2 (IKEv2)", RFC 7427,
              DOI 10.17487/RFC7427, January 2015,
              <http://www.rfc-editor.org/info/rfc7427>.

   [RFC8032]  Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
              Signature Algorithm (EdDSA)", RFC 8032,
              DOI 10.17487/RFC8032, January 2017,
              <http://www.rfc-editor.org/info/rfc8032>.

   [I.D-curdle-pkix]
              Josefsson, S. and J. Schaad, "Algorithm Identifiers for
              Ed25519, Ed25519ph, Ed448, Ed448ph, X25519 and X448 for
              use in the Internet X.509 Public Key Infrastructure",
              March 2017, <https://tools.ietf.org/html/draft-ietf-
              curdle-pkix-04>.

























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Appendix A.  ASN.1 Objects

   The normative reference for the ASN.1 objects for Ed25519 and Ed448
   is in [I.D-curdle-pkix].  They are repeated below for convenience.

A.1.  ASN.1 Object for Ed25519

   id-Ed25519 OBJECT IDENTIFIER ::= { 1.3.101.112 }

   Parameters are absent.  Length is 7 bytes.

   Binary encoding: 3005 0603 2B65 70

A.2.  ASN.1 Object for Ed448

   id-Ed448 OBJECT IDENTIFIER ::= { 1.3.101.113 }

   Parameters are absent.  Length is 7 bytes.

   Binary encoding: 3005 0603 2B65 71

Author's Address

   Yoav Nir
   Check Point Software Technologies Ltd.
   5 Hasolelim st.
   Tel Aviv  6789735
   Israel

   EMail: ynir.ietf@gmail.com





















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