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