Internet DRAFT - draft-ietf-curdle-ssh-ed25519
draft-ietf-curdle-ssh-ed25519
Internet Engineering Task Force B. Harris
Internet-Draft
Updates: 4250 (if approved) L. Velvindron
Intended status: Standards Track Hackers.mu
Expires: August 7, 2018 February 3, 2018
Ed25519 public key algorithm for the Secure Shell (SSH) protocol
draft-ietf-curdle-ssh-ed25519-02
Abstract
This document describes the use of the Ed25519 digital signature
algorithm in the Secure Shell (SSH) 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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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 August 7, 2018.
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.
Harris & Velvindron Expires August 7, 2018 [Page 1]
Internet-Draft Ed25519 for SSH February 2018
1. Introduction
Secure Shell (SSH) [RFC4251] is a secure remote-login protocol. It
provides for an extensible variety of public key algorithms for
identifying servers and users to one another. Ed25519 [RFC8032] is a
digital signature system. OpenSSH 6.5 [OpenSSH-6.5] introduced
support for using Ed25519 for server and user authentication.
Compatible support for Ed25519 has since been added to other SSH
implementations. Ed448 [RFC8032] is another digital signature
system.
This document describes the method implemented by OpenSSH and others,
and formalizes its use of the name "ssh-ed25519". Additionally, it
also describes the use of Ed448 and formalizes its use of the name
"ssh-ed448".
[TO BE REMOVED: Please send comments on this draft to
curdle@ietf.org.]
2. Conventions Used in This Document
The descriptions of key and signature formats use the notation
introduced in [RFC4251], Section 3 [RFC4251] and the string data type
from [RFC4251], Section 5 [RFC4251].
3. Public Key Algorithm
This document describes a public key algorithm for use with SSH in
accordance with [RFC4253], Section 6.6 [RFC4253]. The name of the
algorithm is "ssh-ed25519". This algorithm only supports signing and
not encryption.
Additionally, this document describes another public key algorithm.
The name of the algorithm is "ssh-ed448". This algorithm only
supports signing and not encryption.
4. Public Key Format
The "ssh-ed25519" key format has the following encoding:
string "ssh-ed25519"
string key
Here 'key' is the 32-octet public key described by [RFC8032],
Section 5.1.5 [RFC8032].
Harris & Velvindron Expires August 7, 2018 [Page 2]
Internet-Draft Ed25519 for SSH February 2018
The "ssh-ed448" key format has the following encoding:
string "ssh-ed448"
string key
Here 'key' is the 57-octet public key described by [RFC8032],
Section 5.2.5 [RFC8032].
5. Signature Algorithm
Signatures are generated according to the procedure in [RFC8032],
Section 5.2.6 [RFC8032].
6. Signature Format
The "ssh-ed25519" key format has the following encoding:
string "ssh-ed25519"
string signature
Here 'signature' is the 64-octet signature produced in accordance
with [RFC8032], Section 5.1.6 [RFC8032].
The "ssh-ed448" key format has the following encoding:
string "ssh-ed448"
string signature
Here 'signature' is the 57-octet signature produced in accordance
with [RFC8032], Section 5.2.6 [RFC8032].
7. Verification Algorithm
ED25519 signatures are verified according to the procedure in
[RFC8032], Section 5.1.7 [RFC8032].
ED448 signatures are verified according to the procedure in
[RFC8032], Section 5.2.7 [RFC8032].
8. SSHFP DNS resource records
The generation of SSHFP resource records for "ssh-ed25519" keys is
described in [RFC7479].
The generation of SSHFP resource records for "ssh-ed448" keys is
described in .
Harris & Velvindron Expires August 7, 2018 [Page 3]
Internet-Draft Ed25519 for SSH February 2018
9. IANA Considerations
This document augments the Public Key Algorithm Names in [RFC4250],
Section 4.6.2 [RFC4250].
IANA is requested to add to the Public Key Algorithm Names registry
[IANA-PKA] with the following entry:
Public Key Algorithm Name Reference
------------------------- ----------
ssh-ed25519 This Draft
ssh-ed448 This Draft
[TO BE REMOVED: This registration should take place at the following
location: <http://www.iana.org/assignments/ssh-parameters/ssh-
parameters.xhtml#ssh-parameters-19>]
10. Security Considerations
The security considerations in [RFC4251], Section 9 [RFC4251] apply
to all SSH implementations, including those using Ed25519 and Ed448.
The security considerations in [RFC8032], Section 8 [RFC8032] apply
to all uses of Ed25519 and Ed448 including those in SSH.
11. Acknowledgements
The OpenSSH implementation of Ed25519 in SSH was written by Markus
Friedl.
12. References
12.1. Normative References
[RFC4250] Lehtinen, S. and C. Lonvick, Ed., "The Secure Shell (SSH)
Protocol Assigned Numbers", RFC 4250,
DOI 10.17487/RFC4250, January 2006,
<https://www.rfc-editor.org/info/rfc4250>.
[RFC4251] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Protocol Architecture", RFC 4251, DOI 10.17487/RFC4251,
January 2006, <https://www.rfc-editor.org/info/rfc4251>.
[RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
January 2006, <https://www.rfc-editor.org/info/rfc4253>.
Harris & Velvindron Expires August 7, 2018 [Page 4]
Internet-Draft Ed25519 for SSH February 2018
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>.
12.2. Informative References
[IANA-PKA]
Internet Assigned Numbers Authority (IANA), "Secure Shell
(SSH) Protocol Parameters: Public Key Algorithm Names",
May 2017, <http://www.iana.org/assignments/ssh-parameters/
ssh-parameters.xhtml#ssh-parameters-19>.
[OpenSSH-6.5]
Friedl, M., Provos, N., de Raadt, T., Steves, K., Miller,
D., Tucker, D., Rice, T., and B. Lindstrom, "OpenSSH 6.5
release notes", January 2014,
<http://www.openssh.com/txt/release-6.5>.
[RFC7479] Moonesamy, S., "Using Ed25519 in SSHFP Resource Records",
RFC 7479, DOI 10.17487/RFC7479, March 2015,
<https://www.rfc-editor.org/info/rfc7479>.
Authors' Addresses
Ben Harris
2A Eachard Road
CAMBRIDGE CB3 0HY
UNITED KINGDOM
Email: bjh21@bjh21.me.uk
Loganaden Velvindron
Hackers.mu
88, Avenue De Plevitz
Roches Brunes
Mauritius
Email: logan@hackers.mu
Harris & Velvindron Expires August 7, 2018 [Page 5]