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Shepherd writeup

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

The document type is Standards Track.  The document describes the key
exchange that needs to be supported, deprecated. Such recommendations
are necessary to make implementations interoperable. As such, This is
the appropriated choice. In addition, it updates RFC 4250 which is standard
track. The type is indicated in the header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  Relevant content can frequently be found in the abstract
  and/or introduction of the document. If not, this may be
  an indication that there are deficiencies in the abstract
  or introduction.

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 document updates RFC

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly

The proposed recommendations have been discussed on the mailing
list and in sessions during the IETF in seoul. My impression is that
we have reached consensus as none raised any issue during the WGLC.

Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

The document provides recommendations, as such implementations
are mostly related to the new methods defined in curdle. New key
exchange methods will use the SHA-2 family of hashes and are drawn
from these ssh-curves from [I-D.ietf-curdle-ssh-curves] and new-modp
from the [RFC82682] and gss-keyex [I-D.ietf-curdle-gss-keyex-sha2].

Implementations status of RFC8268 and I-D.ietf-curdle-ssh-curves are
provided below:

* RFC 8268 - new modp groups

      Supported by AsyncSSH
      Supported by OpenSSH
      Supported by Erlang ssh library
      Supported by RLogin
      Supported by SmartFTP
      Supported by Tera Term

      No implementations.

      Supported by AsyncSSH
      Supported by OpenSSH
      Supported by Erlang ssh library
      Supported by SmartFTP

      No implementations.

      Supported by AsyncSSH
      Supported by OpenSSH
      Supported by Erlang ssh library

* draft-ietf-curdle-ssh-curves-06

      Supported by AsyncSSH
      Supported by OpenSSH
      Supported by RLogin
      Supported by SmartFTP

      No support as yet. The biggest stumbling block seems to be that
      examples are not constant time implementations.


  Who is the Document Shepherd? Who is the Responsible Area

Daniel Migault is the document shepherd, Eric Rescorla is the Responsible Area

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

I believe this document is ready to be sent to the IESG.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?


(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.


(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.


(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

The author has confirmed that he is not aware of any IPR.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR

The author has confirmed that he is not aware of any IPR.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it?

I believe the draft reflect some consensus as a fair amount of discussion
happened on the mailing list.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)


(11) Identify any ID nits the Document Shepherd has found in this
document. (See and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be

idnits 2.15.00


  Checking boilerplate required by RFC 5378 and the IETF Trust (see

     No issues found here.

  Checking nits according to

     No issues found here.

  Checking nits according to :

     No issues found here.

  Miscellaneous warnings:

     (Using the creation date from RFC4250, updated by this document, for
     RFC5378 checks: 2005-03-16)

  -- The document seems to lack a disclaimer for pre-RFC5378 work, but may
     have content which was first submitted before 10 November 2008.  If you
     have contacted all the original authors and they are all willing to grant
     the BCP78 rights to the IETF Trust, then this is fine, and you can ignore
     this comment.  If not, you may need to add the pre-RFC5378 disclaimer.
     (See the Legal Provisions document at for more information.)

  Checking references for intended status: Proposed Standard

     (See RFCs 3967 and 4897 for information about using normative references
     to lower-maturity documents in RFCs)

  == Outdated reference: A later version (-07) exists of

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.


(13) Have all references within this document been identified as
either normative or informative?

All references have been identified as Normative or Informational.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

draft-ietf-curdle-ssh-curves and draft-ietf-curdle-gss-keyex-sha2 need
to be published. draft-ietf-curdle-gss-keyex-sha2 is expected to be
submitted soon to the IESG, while draft-ietf-curdle-ssh-curves has been
already submitted.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.


I suspect that SSH / GSS / IKEv2 protocol RFC could be moved from informational
to normative.

 [RFC4251]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Protocol Architecture", RFC 4251, DOI 10.17487/RFC4251,
              January 2006, <>.

   [RFC4419]  Friedl, M., Provos, N., and W. Simpson, "Diffie-Hellman
              Group Exchange for the Secure Shell (SSH) Transport Layer
              Protocol", RFC 4419, DOI 10.17487/RFC4419, March 2006,

   [RFC4432]  Harris, B., "RSA Key Exchange for the Secure Shell (SSH)
              Transport Layer Protocol", RFC 4432, DOI 10.17487/RFC4432,
              March 2006, <>.

   [RFC4462]  Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch,
              "Generic Security Service Application Program Interface
              (GSS-API) Authentication and Key Exchange for the Secure
              Shell (SSH) Protocol", RFC 4462, DOI 10.17487/RFC4462, May
              2006, <>.

   [RFC5656]  Stebila, D. and J. Green, "Elliptic Curve Algorithm
              Integration in the Secure Shell Transport Layer",
              RFC 5656, DOI 10.17487/RFC5656, December 2009,

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <>.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

This document will change the status of RFC 4250. This has been
indicated in the header, the abstract and the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The IANA consideration seems fine to me. No new code point are requested.
The IANA is requested to update the registry by indicating the current
document as a reference of deprecated algorithms.

Updating the registry requires IETF review which is achieved by this document.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.


(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.