Using the Edwards-Curve Digital Signature Algorithm (EdDSA) in the Internet Key Exchange Protocol Version 2 (IKEv2)
RFC 8420

Document Type RFC - Proposed Standard (August 2018; No errata)
Last updated 2018-08-20
Replaces draft-nir-ipsecme-eddsa
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Send notices to "Tero Kivinen" <kivinen@iki.fi>
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Internet Engineering Task Force (IETF)                            Y. Nir
Request for Comments: 8420                                      Dell EMC
Category: Standards Track                                    August 2018
ISSN: 2070-1721

   Using the Edwards-Curve Digital Signature Algorithm (EdDSA) in the
            Internet Key Exchange Protocol Version 2 (IKEv2)

Abstract

   This document describes the use of the Edwards-curve Digital
   Signature Algorithm (EdDSA) in the Internet Key Exchange Protocol
   Version 2 (IKEv2).

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
   https://www.rfc-editor.org/info/rfc8420.

Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) 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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Nir                          Standards Track                    [Page 1]
RFC 8420                     EdDSA in IKEv2                  August 2018

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 .........................................4
     A.1.  ASN.1 Object for Ed25519 ...................................4
     A.2.  ASN.1 Object for Ed448 .....................................4
   Author's Address ...................................................5

1.  Introduction

   The Internet Key Exchange Protocol Version 2 [RFC7296] can use
   arbitrary signature algorithms as described in [RFC7427].  [RFC7427]
   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
   prehashing of the message.  Unlike other methods, these accept
   messages of arbitrary size, so no prehashing is required.  These
   methods are called Ed25519 and Ed448; they use the Edwards 25519 and
   the Edwards 448 ("Goldilocks") curves, respectively.  Although that
   document also defines prehashed versions of these algorithms, those
   versions are not recommended for protocols where there is minimal
   burden in buffering the entire message so as to make it practical to
   make two passes over the message.  This is true of IKEv2.  See
   Section 8.5 of [RFC8032] 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 of RFC 8032.  [RFC8410] 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 in the SIGNATURE_HASH_ALGORITHMS notification to
   indicate that no hashing is performed.

Nir                          Standards Track                    [Page 2]
RFC 8420                     EdDSA in IKEv2                  August 2018

1.1.  Conventions Used in This Document

   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 "Identity" Hash Identifier

   This document defines a new value called "Identity" (5) in the "IKEv2
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