Internet DRAFT - draft-bjh21-ssh-ed25519
draft-bjh21-ssh-ed25519
Network Working Group B. Harris
Internet-Draft August 1, 2015
Intended status: Informational
Expires: February 2, 2016
Ed25519 public key algorithm for the Secure Shell (SSH) protocol
draft-bjh21-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
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This Internet-Draft will expire on February 2, 2016.
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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
[I-D.josefsson-eddsa-ed25519] 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.
This document describes the method implemented by OpenSSH and others,
and formalizes its use of the name "ssh-ed25519".
Comments on this draft are welcomed and should be sent to the author.
2. Conventions Used in This Document
The descriptions of key and signature formats use the notation
introduced in [RFC4251], Section 3 and the string data type from
[RFC4251], Section 5.
3. Public Key Algorithm
This document describes a public key algorithm for use with SSH in
accordance with [RFC4253], Section 6.6. The name of the algorithm is
"ssh-ed25519". 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
[I-D.josefsson-eddsa-ed25519], Section 5.5.
5. Signature Algorithm
Signatures are generated according to the procedure in
[I-D.josefsson-eddsa-ed25519], Section 5.6.
6. Signature format
The corresponding signature format is:
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string "ssh-ed25519"
string signature
Here 'signature' is the 64-octet signature produced in accordance
with [I-D.josefsson-eddsa-ed25519], Section 5.6.
7. Verification Algorithm
Signatures are verified according to the procedure in
[I-D.josefsson-eddsa-ed25519], Section 5.7.
8. SSHFP DNS resource records
The generation of SSHFP resource records for "ssh-ed25519" keys is
described in [RFC7479].
9. IANA Considerations
IANA is requested to assign the Public Key Algorithm name
"ssh-ed25519" in accordance with [RFC4250], Section 4.6.2:
Public Key Algorithm Name Reference
------------------------- ---------
ssh-ed25519 [RFCXXXX]
[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 apply to all SSH
implementations, including those using Ed25519.
The security considerations in [I-D.josefsson-eddsa-ed25519],
Section 9 apply to all uses of Ed25519, including those in SSH.
11. Acknowledgements
The OpenSSH implementation of Ed25519 in SSH was written by Markus
Friedl.
12. References
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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,
<http://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, <http://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, <http://www.rfc-editor.org/info/rfc4253>.
[I-D.josefsson-eddsa-ed25519]
Josefsson, S. and N. Moller, "EdDSA and Ed25519", draft-
josefsson-eddsa-ed25519-03 (work in progress), May 2015.
12.2. Informative References
[RFC7479] Moonesamy, S., "Using Ed25519 in SSHFP Resource Records",
RFC 7479, DOI 10.17487/RFC7479, March 2015,
<http://www.rfc-editor.org/info/rfc7479>.
[OpenSSH-6.5]
Friedl, M., Provos, N., de Raadt, T., Steves, K., Miller,
D., Tucker, D., McIntyre, J., Rice, T., and B. Lindstrom,
"[OpenSSH 6.5 release notes]", January 2014,
<http://www.openssh.com/txt/release-6.5>.
Author's Address
Ben Harris
2A Eachard Road
CAMBRIDGE CB3 0HY
UNITED KINGDOM
Email: bjh21@bjh21.me.uk
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