Key Exchange (KEX) Method Updates and Recommendations for Secure Shell (SSH)
draft-ietf-curdle-ssh-kex-sha2-07
Internet Engineering Task Force M. Baushke
Internet-Draft Juniper Networks, Inc.
Updates: 4250, 4253 (if approved) March 27, 2017
Intended status: Standards Track
Expires: September 28, 2017
Key Exchange (KEX) Method Updates and Recommendations for Secure Shell
(SSH)
draft-ietf-curdle-ssh-kex-sha2-07
Abstract
This document is intended to update the recommended set of key
exchange methods for use in the Secure Shell (SSH) protocol to meet
evolving needs for stronger security. This RFC updates [RFC4253]
MUST algorithms. This RFC also notes that the [IANASSH] has replaced
[RFC4250] as the primary reference document for SSH Protocol Assigned
Numbers.
This document adds recommendations for adoption of Key Exchange
Methods which MUST, SHOULD+, SHOULD, SHOULD-, MAY, SHOULD NOT, and
MUST NOT be implemented. New key exchange methods will use the SHA-2
family of hashes and are drawn from these from
[I-D.ietf-curdle-ssh-curves] and new-modp from the
[I-D.ietf-curdle-ssh-modp-dh-sha2] and gss-keyex [NEWGSSAPI].
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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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 September 28, 2017.
Baushke Expires September 28, 2017 [Page 1]
Internet-Draft KEX Method Updates/Recommendations for SSH March 2017
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Table of Contents
1. Overview and Rationale . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Key Exchange Methods . . . . . . . . . . . . . . . . . . . . 3
3.1. curve25519-sha256 . . . . . . . . . . . . . . . . . . . . 4
3.2. diffie-hellman-group-exchange-sha1 . . . . . . . . . . . 4
3.3. diffie-hellman-group1-sha1 . . . . . . . . . . . . . . . 4
3.4. diffie-hellman-group14-sha1 . . . . . . . . . . . . . . . 4
3.5. diffie-hellman-group14-sha256 . . . . . . . . . . . . . . 4
3.6. diffie-hellman-group16-sha512 . . . . . . . . . . . . . . 4
3.7. ecdh-sha2-nistp256 . . . . . . . . . . . . . . . . . . . 5
3.8. ecdh-sha2-nistp384 . . . . . . . . . . . . . . . . . . . 5
3.9. gss-gex-sha1-* . . . . . . . . . . . . . . . . . . . . . 5
3.10. gss-group1-sha1-* . . . . . . . . . . . . . . . . . . . . 5
3.11. gss-group14-sha1-* . . . . . . . . . . . . . . . . . . . 5
3.12. gss-group14-sha256-* . . . . . . . . . . . . . . . . . . 6
3.13. gss-group16-sha512-* . . . . . . . . . . . . . . . . . . 6
3.14. rsa1024-sha1 . . . . . . . . . . . . . . . . . . . . . . 6
4. Summary Guidance for Key Exchange Method Names . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Overview and Rationale
Secure Shell (SSH) is a common protocol for secure communication on
the Internet. In [RFC4253], SSH originally defined two Key Exchange
Method Names that MUST be implemented. Over time, what was once
considered secure, is no longer considered secure. The purpose of
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