Deprecate Triple-DES (3DES) and RC4 in Kerberos
draft-ietf-curdle-des-des-des-die-die-die-05

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has completed its review of draft-ietf-curdle-des-des-des-die-die-die-05. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there are two actions which we must complete.

First, in the Kerberos Encryption Type Numbers registry on the Kerberos Parameters registry page located at:

https://www.iana.org/assignments/kerberos-parameters/

Encryption types 1, 2, 3, and 24 are to be marked as deprecated and the reference is to be changed to RFC 6649. In addition, encryption types 5, 7, 16, and 23 are deprecated, with this [ RFC-to-be ] as the reference.

Second, in the Kerberos Checksum Type Numbers registry also on the Kerberos Parameters registry page located at:

https://www.iana.org/assignments/kerberos-parameters/

Checksum types 1, 2, 3, 4, 5, 6, and 8 are to be deprecated, with RFC 6649 as the reference. In addition, checksum types 7, 12, and 13 are deprecated, with [ RFC-to-be ] as the reference.

The IANA Services Operator understands that these two actions are the only ones required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2018-04-24):

From: The IESG
To: IETF-Announce
CC: ekr@rtfm.com, draft-ietf-curdle-des-des-des-die-die-die@ietf.org, Daniel Migault , curdle-chairs@ietf.org, curdle@ietf.org, daniel.migault@ericsson.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Deprecate 3DES and RC4 in Kerberos) to Best Current Practice


The IESG has received a request from the CURves, Deprecating and a Little
more Encryption WG (curdle) to consider the following document: - 'Deprecate
3DES and RC4 in Kerberos'
  as Best Current Practice

The Last Call for the document draft-ietf-curdle-des-des-des-die-die-die is related to
the status change document, also in Last Call, for status-change-kerberos-3des-rc4-to-historic.

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2018-04-24. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.

Abstract


  The 3DES and RC4 encryption types are steadily weakening in
  cryptographic strength, and the deprecation process should be begun
  for their use in Kerberos.  Accordingly, RFC 4757 is moved to
  Historic status, as none of the encryption types it specifies should
  be used, and RFC 3961 is updated to note the deprecation of the
  triple-DES encryption types.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-curdle-des-des-des-die-die-die/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-curdle-des-des-des-die-die-die/ballot/


No IPR declarations have been submitted directly on this I-D.


The document contains these normative downward references.
See RFC 3967 for additional information:
    rfc3961: Encryption and Checksum Specifications for Kerberos 5 (Proposed Standard - IETF stream)
    rfc4120: The Kerberos Network Authentication Service (V5) (Proposed Standard - IETF stream)

[Ballot comment]
Although there is precedent for obsoleting a spec and making it historical at the same time, I agree with Mirja that it doesn't seem to make sense in most cases.

[Ballot comment]
I agree with Mirja that is seems more appropriate to move RFC4757 to historic.  I'm guessing the choice for obsolete was because of deprecating the algorithms used in the implementation.  Thanks for your work on this draft.

[Ballot comment]
I agree with Mirja's points about Obsoletes vs. Historic, and I didn't think we required a status change document for *all* move-to-Historic status changes, but https://www.ietf.org/iesg/statement/designating-rfcs-as-historic.html says that we do.

On the brighter side, that may be the best draft filename I've seen as an AD ...

[Ballot comment]
Thanks to Joel for his OpsDir review.

I have a few comments / readability suggestions:
1: Section 5.1.  Statistical Biases
"These attacks seem to rely on repeated encryptions of thousands of copies of the same plaintext; " -- for a document which deprecates rc4-hmac the "seem to rely on" feels very weak. I'd suggest s/seem// or "At least some of these attacks rely on..." or similar.

2: Section 6.  3DES Weakness
"Additionally, the 3DES encryption types were never implemented in all Kerberos implementations..."
s/never/not/

3:  Section 6.3.  Interoperability
"The triple-DES encryption types were implemented by MIT Kerberos
  early in its development (ca. 1999) and present in the 1.2 release,
  but encryption types 17 and 18 (AES) were implemented by 2003 and
  present in the 1.3 release."
I'm a bit confused by the "but" - should this be "and"? Otherwise it sounds like it it trying to contrast something.

[Ballot discuss]
This is mainly a processing question, so probably more for the IESG to discuss than the authors:

I understand the intention of obsoleting RFC4757 to declare that the algorithms described should not be used anymore, however, rfc4757 is an informational implementation description which is probably still deployed. Obsoleting an informational implementation description seems a bit weird. Just would like to double-check with the rest of the IESG if that action appropriate...?

Also obsoleting and moving to historic is not the same thing. The document says:
"This document recommends the reclassification of [RFC4757] as Historic."
One of the two actions (obsoleting or moving to historic) is enough. While I think moving to historic might actually be more appropriate than obsoleting an implementation description, it should only be moved to historic if this is not used and deployed anymore. Also moving to historic also requires a status change action.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has completed its review of draft-ietf-curdle-des-des-des-die-die-die-03. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there are two actions which we must complete.

First, in the Kerberos Encryption Type Numbers registry on the Kerberos Parameters registry page located at:

https://www.iana.org/assignments/kerberos-parameters/

Encryption types 1, 2, 3, and 24 are to be marked as deprecated and the reference is to be changed to RFC 6649. In addition, encryption types 5, 7, 16, and 23 are deprecated, with this [ RFC-to-be ] as the reference.

Second, in the Kerberos Checksum Type Numbers registry also on the Kerberos Parameters registry page located at:

https://www.iana.org/assignments/kerberos-parameters/

Checksum types 1, 2, 3, 4, 5, 6, and 8 are to be deprecated, with RFC 6649 as the reference. In addition, checksum types 7, 12, and 13 are deprecated, with [ RFC-to-be ] as the reference.

The IANA Services Operator understands that these two actions are the only ones required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.


Thank you,

Sabrina Tanamal
IANA Services Specialist
PTI

The following Last Call announcement was sent out (ends 2017-07-30):

From: The IESG
To: IETF-Announce
CC: ekr@rtfm.com, draft-ietf-curdle-des-des-des-die-die-die@ietf.org, Daniel Migault , curdle-chairs@ietf.org, curdle@ietf.org, daniel.migault@ericsson.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Deprecate 3DES and RC4 in Kerberos) to Best Current Practice


The IESG has received a request from the CURves, Deprecating and a Little
more Encryption WG (curdle) to consider the following document: - 'Deprecate
3DES and RC4 in Kerberos'
  as Best Current Practice

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2017-07-30. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.

Abstract


  The 3DES and RC4 encryption types are steadily weakening in
  cryptographic strength, and the deprecation process should be begun
  for their use in Kerberos.  Accordingly, RFC 4757 is moved to
  Obsolete status, as none of the encryption types it specifies should
  be used, and RFC 3961 is updated to note the deprecation of the
  triple-DES encryption types.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-curdle-des-des-des-die-die-die/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-curdle-des-des-des-die-die-die/ballot/


No IPR declarations have been submitted directly on this I-D.


The document contains these normative downward references.
See RFC 3967 for additional information:
    rfc3961: Encryption and Checksum Specifications for Kerberos 5 (Proposed Standard - IETF stream)
    rfc4120: The Kerberos Network Authentication Service (V5) (Proposed Standard - IETF stream)

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 target is BCP which is indicated in the header. According to
RFC1818 BCP are used to publish relevant technical information
endorsed by the IETF community.  This document recommend
not to use weak ciphers. This could fall under the BCP. In addition
rfc6649 "Deprecate DES, RC4-HMAC-EXP, and Other Weak
Cryptographic Algorithms in Kerberos" has BCP as a status. 

The draft updates  RFC 3961  and obsoletes RFC 4757. This is mentioned
in the header, abstract and introduction.

(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.

The 3DES and RC4 encryption types are steadily weakening in
cryptographic strength, and the deprecation process should be begun
for their use in Kerberos.  Accordingly, RFC 4757 is moved to
Obsolete status, as none of the encryption types it specifies should
be used, and RFC 3961 is updated to note the deprecation of the
triple-DES encryption types.

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
  rough?

No controversy.

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?

This does not apply here.

My understanding is implementations are likely to implement
the draft, especially with the "SHOULD NOT" recommendation.

Both co-authors expect to start the deprecation process which is slow
to achieve as there is now a long deployment history. A deprecation
will not remove the actual software  implementation right away, but
progressively disable it.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Daniel Migault is the shepherd, Eric Rescola is the AD

(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.


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

No. The document has been written and supported by major implementations
of Kerberos, and has benefited from a significant number of reviews.

(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.

This does not apply here.

(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.

I have no issue with the document.

(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.

Both co-authors state they are 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
disclosures.

No.

(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? 

Yes.

(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.)

No.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

The latest version provides teh following nits:

  Checking nits according to http://www.ietf.org/id-info/checklist :
  ----------------------------------------------------------------------------

  -- The draft header indicates that this document obsoletes RFC4757, but the
    abstract doesn't seem to directly say this.  It does mention RFC4757
    though, so this could be OK.

  -- The draft header indicates that this document updates RFC3961, but the
    abstract doesn't seem to directly say this.  It does mention RFC3961
    though, so this could be OK.

MGLT: This is OK, the abstract mentions: """Accordingly, RFC 4757 is moved to
  Obsolete status, as none of the encryption types it specifies should
  be used, and RFC 3961 is updated to note the deprecation of the
  triple-DES encryption types."""

This is probably due to the space between RFC and the number.

  Miscellaneous warnings:
  ----------------------------------------------------------------------------

    (Using the creation date from RFC3961, updated by this document, for
    RFC5378 checks: 2004-02-11)

  -- 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
    http://trustee.ietf.org/license-info for more information.)

MGLT: I do not think this applies here as well. There is no copy past from the pre-RFC5378 work.

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

This does not apply here.

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

Yes.

(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?

No.

(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.

No.

(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.

The current document obsoletes: 4757 and updates: 3961. This is mentioned
in the abstract and in the header 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 section is consequent with body of the text.

Encryption types 5, 7, 16, and 23 are deprecated, with this document
as the reference. We checked with IANA whether the reference should
be the reference introducing the registry entry or the one deprecating
it. From there response, there is no specific rule for it. Having the
reference deprecating the entry is fine.


Note that the the IANA is also requested to  update status checksum 
types 1, 2, 3, 4, 5, 6, and 8 that are deprecated, with RFC 6649. 


(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.

Standards Action for standards-track RFCs; non-standards-track
RFCs must be reviewed by an expert. The proposed expert is Ken Raeburn.

(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.

This does not apply here.