6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs)
draft-ietf-6lo-ghc-05

[Ballot comment]
Has consideration been given to the security impacts of compressing headers withing encrypted payloads?  In the context of HTTPS, there have been several attacks that exploited TLS compression in order recover information about secret values.  These attacks are possible because the compression used a dictionary that was dynamically constructed based on the content sent over the channel.  This allows an attacker to probe for a secret value by sending guesses and seeing if the response is compressed.  It seems like the backreference mechanism in this document could have similar repercussions if backreferences were allowed over a sufficiently broad scope. 

It may be helpful to consult the Security Considerations in the HTTP header compression draft:
https://tools.ietf.org/html/draft-ietf-httpbis-header-compression-09

"that can be defined on a single page" - I note that this document is more than one page long, even discounting boilerplate :)

It would nice if you would explain where the magical 16-byte dictionary comes from.

What do the underscores in Figure 5 mean?  If this notation is defined elsewhere, please reference.

[Ballot discuss]
Has consideration been given to the security impacts of compressing headers withing encrypted payloads?  In the context of HTTPS, there have been several attacks that exploited TLS compression in order recover information about secret values.  These attacks are possible because the compression used a dictionary that was dynamically constructed based on the content sent over the channel.  This allows an attacker to probe for a secret value by sending guesses and seeing if the response is compressed.  It seems like the backreference mechanism in this document could have similar repercussions if backreferences were allowed over a sufficiently broad scope. 

It may be helpful to consult the Security Considerations in the HTTP header compression draft:
https://tools.ietf.org/html/draft-ietf-httpbis-header-compression-09

[Ballot comment]
"that can be defined on a single page" - I note that this document is more than one page long, even discounting boilerplate :)

It would nice if you would explain where the magical 16-byte dictionary comes from.

What do the underscores in Figure 5 mean?  If this notation is defined elsewhere, please reference.

[Ballot comment]
  where 0 stands for 0, 1 for 1

I can't tell you how relieved I am to see that.

  For the purposes of the IANA registry,
  the bits are numbered in most-significant-bit-first order from the
  16th bit of the option onward, i.e., the G bit is flag number 15.

A minor thing -- but I had to read the paragraph a couple of times before I got the point this sentence is making:  Perhaps...

NEW
  For the purposes of the IANA registry,
  the bits are numbered in most-significant-bit-first order from the
  16th bit of the option onward: the 16th bit is flag number 0, and
  the 31st bit (the G bit) is flag number 15.
END

[Ballot comment]

- abstract: 23 pages isn't very short:-)

- GHC is used before expansion I think.

- Has anyone had a look to see if there is a way to craft
compressed packets that would be (very) costly on the
receiver when decompressed? (As a DoS acceleraor say.) That
can be an issue for some compression schemes but I'n not sure
if its one here or not. (Sorry, haven't had time to figure
that out myself yet, and maybe its quicker to ask:-)

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-6lo-ghc-03.  Authors should review the comments and/or questions below.  Please report any inaccuracies and respond to any questions as soon as possible.

We received the following comments/questions from the IANA's reviewer:

IANA understands that, upon approval of this document, there are three actions which IANA must complete.

First, in the LOWPAN_NHC Header Type subregistry of the IPv6 Low Power Personal Area Network Parameters registry located at:

http://www.iana.org/assignments/_6lowpan-parameters/

three new Header Types are to be registered as follows:

Value: 10110IIN
Description: Extension header GHC
Reference: [ RFC-to-be ]

Value: 11010CPP
Description: UDP GHC
Reference: [ RFC-to-be ]

Value: 11011111
Description: ICMPv6 GHC
Reference: [ RFC-to-be ]

Second, in the IPv6 Neighbor Discovery Option Formats subregistry of the Internet Control Message Protocol version 6 (ICMPv6) Parameters registry located at:

http://www.iana.org/assignments/icmpv6-parameters/

a new Option Format is to bew registered as follows:

Type: [ TBD-at-registration ]
Description: 6CIO ND Option
Reference: [ RFC-to-be ]

Third, a new subregistry called the 6LoWPAN capability registry is to be created in the Internet Control Message Protocol version 6 (ICMPv6) Parameters registry located at:

http://www.iana.org/assignments/icmpv6-parameters/

The registry is to be maintained through IETF Review or "IESG Approval" as defined in RFC 5226. There are initial registrations in this new subregistry as follows:

Capability
Bit Description Reference
-----------+------------------------------------------------+-------------
0-7 Reserved for experiments [ RFC-to-be ]
8-14 Unassigned [ RFC-to-be ]
15 GHC Capable Bit (G bit) [ RFC-to-be ]
16-47 Unassigned [ RFC-to-be ]

IANA understands that these three actions are the only one 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. 

Please note that IANA cannot reserve specific values. However, early allocation is available for some types of registrations. For more information, please see RFC 7120.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC: <6lo@ietf.org>
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (6LoWPAN Generic Compression of Headers and Header-like Payloads) to Proposed Standard


The IESG has received a request from the IPv6 over Networks of
Resource-constrained Nodes WG (6lo) to consider the following document:
- '6LoWPAN Generic Compression of Headers and Header-like Payloads'
  as Proposed Standard

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 2014-08-29. 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


  This short specification provides a simple addition to 6LoWPAN Header
  Compression that enables the compression of generic headers and
  header-like payloads, without a need to define a new header
  compression scheme for each new such header or header-like payload.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-6lo-ghc/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-6lo-ghc/ballot/


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

(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?

        Publication as Proposed Standard is requested. This is indicated in the title
        page header.

        The document is well-understood by the community, extensively reviewed
        and considered technically solid by the WG.

(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:
        This short specification provides a simple addition to 6LoWPAN Header
        Compression that enables the compression of generic headers and
        header-like payloads, without a need to define a new header
        compression scheme for each new such header or header-like payload.


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?

        There were no particular points of contention in the WG process, and the
        consensus behind publication of this document as a Standards Track RFC
        appears solid.

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?

        There are multiple experimental implementations.
        There have been no specific MIB doctor, Media Type or other expert reviews
        done.

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

        The Document Shepherd is Ulrich Herberg.
        The Responsible Area Director is Brian Haberman.

(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.

        The document shepherd has reviewed this document, both as part of the
        WG process, and prior to the issuance of the Publication Request.
        The document shepherd believes that this version of the document is
        ready for publication.

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

        The document shepherd has no concerns with the depth or
        breadth of the reviews of this document.

(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 document does not need reviews beyond those normally done during
        AD and IESG processing.

(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.

        The document shepherd has no specific concerns with this 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?

        Each author has confirmed that they are not aware of any IPR requiring
        disclosure.

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

        No IPR disclosures have been filed, referencing this document.

(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?

        There has been solid WG consensus with understanding and agreement
        of the whole WG.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarize 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 appeals have been threatened.
        No extreme discontent has been indicated.

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

        IDNIT returns one minor warning (reference to "RFCthis").
        This will we be replaced by the RFC editor.

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

        There is no required MIB doctor, media type, URI type or other formal review.

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

        All references have been identified as either normative or informative.

(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?

        All normative references are to already published RFC at the same,
        or on a higher, maturity level.

(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.

        There are no downward references.

(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 does not change the status of any existing RFCs.

(17) Describe the Document Shepherd's review of the IANA considerations section, especially with regard to its consistency with the body of the document.

        The document shepherd has reviewed the IANA considerations section, which
        is both consistent with the body of the document.

Confirm that all protocol extensions that the document makes are associated with the appropriate reservations in IANA registries.

        This is confirmed.

Confirm that any referenced IANA registries have been clearly identified.

        All 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).

        This is confirmed.

(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.

        None of the new requested IANA registries require Expert Review for future
        allocations.

(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 document does not contain any sections written in a formal language.