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HPACK: Header Compression for HTTP/2
RFC 7541

Revision differences

Document history

Date Rev. By Action
2015-10-14
12 (System) Notify list changed from draft-ietf-httpbis-header-compression@ietf.org, httpbis-chairs@ietf.org to (None)
2015-05-14
12 (System) RFC published
2015-05-09
12 (System) RFC Editor state changed to AUTH48-DONE from AUTH48
2015-04-27
12 (System) RFC Editor state changed to AUTH48 from RFC-EDITOR
2015-04-16
12 (System) RFC Editor state changed to RFC-EDITOR from REF
2015-03-26
12 (System) RFC Editor state changed to REF from EDIT
2015-02-24
12 (System) RFC Editor state changed to EDIT from IESG
2015-02-23
12 (System) RFC Editor state changed to IESG from EDIT
2015-02-19
12 Amy Vezza IESG state changed to RFC Ed Queue from Approved-announcement sent
2015-02-19
12 (System) RFC Editor state changed to EDIT
2015-02-19
12 (System) Announcement was received by RFC Editor
2015-02-17
12 Barry Leiba Notification list changed to draft-ietf-httpbis-header-compression@ietf.org, httpbis-chairs@ietf.org from mnot@mnot.net, draft-ietf-httpbis-header-compression.all@ietf.org, httpbis-chairs@ietf.org, ietf-http-wg@w3.org
2015-02-17
12 (System) IANA Action state changed to No IC from In Progress
2015-02-17
12 (System) IANA Action state changed to In Progress
2015-02-17
12 Cindy Morgan IESG state changed to Approved-announcement sent from Approved-announcement to be sent
2015-02-17
12 Cindy Morgan IESG has approved the document
2015-02-17
12 Cindy Morgan Closed "Approve" ballot
2015-02-17
12 Cindy Morgan Ballot approval text was generated
2015-02-17
12 Barry Leiba IESG state changed to Approved-announcement to be sent from Approved-announcement to be sent::Point Raised - writeup needed
2015-02-17
12 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-12.txt
2015-02-10
11 Herve Ruellan IANA Review state changed to Version Changed - Review Needed from IANA OK - No Actions Needed
2015-02-10
11 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-11.txt
2015-01-22
10 Cindy Morgan IESG state changed to Approved-announcement to be sent::Point Raised - writeup needed from IESG Evaluation
2015-01-22
10 Tero Kivinen Request for Last Call review by SECDIR Completed: Has Nits. Reviewer: Matt Lepinski.
2015-01-22
10 Benoît Claise
[Ballot comment]
Similar to Jari's COMMENT.
David Black, part of the combined OPS/GEN-ART review (http://www.ietf.org/mail-archive/web/gen-art/current/msg11197.html) mentions:

The second major issue looks serious - …
[Ballot comment]
Similar to Jari's COMMENT.
David Black, part of the combined OPS/GEN-ART review (http://www.ietf.org/mail-archive/web/gen-art/current/msg11197.html) mentions:

The second major issue looks serious - one of the major motivations
for HPACK is to mitigate attacks on DEFLATE (e.g., CRIME) via use of never
indexed fields wrt compression.  The absence of a list of header fields
that MUST use that never indexed functionality appears to be a serious
oversight.

This point was discussed during the IESG telechat and, according to the Sec ADs, this is not an issue: list of header that should never be compressed, will change in response to the attach. Stephen and Kathleen will follow up on the list.
2015-01-22
10 Benoît Claise [Ballot Position Update] Position for Benoit Claise has been changed to No Objection from Discuss
2015-01-22
10 Ted Lemon [Ballot Position Update] New position, No Objection, has been recorded for Ted Lemon
2015-01-22
10 Amy Vezza Changed consensus to Yes from Unknown
2015-01-22
10 Benoît Claise
[Ballot discuss]
Similar to Jari's COMMENT.
David Black, part of the combined OPS/GEN-ART review (http://www.ietf.org/mail-archive/web/gen-art/current/msg11197.html) mentions:

The second major issue looks serious - …
[Ballot discuss]
Similar to Jari's COMMENT.
David Black, part of the combined OPS/GEN-ART review (http://www.ietf.org/mail-archive/web/gen-art/current/msg11197.html) mentions:

The second major issue looks serious - one of the major motivations
for HPACK is to mitigate attacks on DEFLATE (e.g., CRIME) via use of never
indexed fields wrt compression.  The absence of a list of header fields
that MUST use that never indexed functionality appears to be a serious
oversight.

Could I ask one of you to place a Discuss to ensure that these concerns
are addressed?

====================
I haven't had the time to read the draft (shocking I know). So I'm unclear at this point if the feedback is DISCUSS/COMMENT-worthy, but ... I've got a very high respect for David's technical reviews. In many years of review, it's the first time he directly asked me to file a DISCUSS. So I want to go to the bottom of this issue. If this approach is clumsy (yes, I know, the DISCUSS should be in my name, not on behalf of David), I could also "DEFER" this draft. 
I also see that the authors/David engaged in the discussion on the ietf@ietf.org list. Good.
2015-01-22
10 Benoît Claise [Ballot Position Update] New position, Discuss, has been recorded for Benoit Claise
2015-01-22
10 Stephen Farrell [Ballot comment]


Excellent stuff! A well-written clear description of a
reasonably complex thing.
2015-01-22
10 Stephen Farrell [Ballot Position Update] New position, Yes, has been recorded for Stephen Farrell
2015-01-22
10 Jari Arkko
[Ballot comment]
David Black's Gen-ART review raised the issue of never-indexed fields, and whether guidance or a list of header fields should be in the …
[Ballot comment]
David Black's Gen-ART review raised the issue of never-indexed fields, and whether guidance or a list of header fields should be in the document to describe when this option should be used. Has the WG discussed this in the past, and what conclusion did it came to? Are there standardised header fields that would clearly be on such a list, if it were given in the document?
2015-01-22
10 Jari Arkko [Ballot Position Update] New position, Yes, has been recorded for Jari Arkko
2015-01-22
10 Brian Haberman [Ballot Position Update] New position, No Objection, has been recorded for Brian Haberman
2015-01-21
10 Joel Jaeggli [Ballot Position Update] New position, No Objection, has been recorded for Joel Jaeggli
2015-01-21
10 Spencer Dawkins [Ballot Position Update] New position, No Objection, has been recorded for Spencer Dawkins
2015-01-21
10 Richard Barnes
[Ballot comment]
Section 2.3.3: "Indices between 1 and the length of the static table..."
The use of 1-based indexing here seems likely to lead to …
[Ballot comment]
Section 2.3.3: "Indices between 1 and the length of the static table..."
The use of 1-based indexing here seems likely to lead to incompatibilities.

Section 3:
Currently, you never say explicitly that a header block is the concatenation of encoded header fields, where each field is encoded according to Section 6.  This would be a good spot to do that.

Section 5.1: "... always finishes at the end of an octet"
It was not immediately clear to me that the "?" bits indicated that an integer need not *begin* at an octet boundary.  It would be helpful to note that here.
2015-01-21
10 Richard Barnes [Ballot Position Update] New position, Yes, has been recorded for Richard Barnes
2015-01-21
10 Alia Atlas [Ballot Position Update] New position, No Objection, has been recorded for Alia Atlas
2015-01-21
10 Pete Resnick [Ballot Position Update] New position, No Objection, has been recorded for Pete Resnick
2015-01-21
10 Kathleen Moriarty
[Ballot comment]
Thank you for your work on this draft and for the thorough security considerations section.  I do agree with the SecDir reviewer that …
[Ballot comment]
Thank you for your work on this draft and for the thorough security considerations section.  I do agree with the SecDir reviewer that an early reference to the security considerations section would be useful, please consider adding that.

http://www.ietf.org/mail-archive/web/secdir/current/msg05406.html

Another good point is that while this draft addresses current threats (CRIME), the WG should keep in mind that the attacks could evolve.  This is really just to think ahead with options since HPACK is a relatively new algorithm, and since encryption of compressed headers is known to be somewhat perilous.  It is possible that a clever attacker will develop a new attack in the future (i.e., CRIME++ ) that works against HPACK-compressed header fields.
2015-01-21
10 Kathleen Moriarty [Ballot Position Update] New position, Yes, has been recorded for Kathleen Moriarty
2015-01-21
10 Alissa Cooper
[Ballot comment]
My one question about this was about lack of extensibility of the static table, but I see that some intro text has been …
[Ballot comment]
My one question about this was about lack of extensibility of the static table, but I see that some intro text has been added to the editor's copy of the document  that speaks to this. Keeping that text would be good imo.
2015-01-21
10 Alissa Cooper [Ballot Position Update] New position, No Objection, has been recorded for Alissa Cooper
2015-01-21
10 Adrian Farrel [Ballot Position Update] New position, No Objection, has been recorded for Adrian Farrel
2015-01-21
10 Martin Stiemerling [Ballot comment]
I just wonder if there is a second implementation, the shepherd report is pointing out one.
2015-01-21
10 Martin Stiemerling [Ballot Position Update] New position, No Objection, has been recorded for Martin Stiemerling
2015-01-17
10 Barry Leiba Ballot has been issued
2015-01-17
10 Barry Leiba [Ballot Position Update] New position, Yes, has been recorded for Barry Leiba
2015-01-17
10 Barry Leiba Created "Approve" ballot
2015-01-17
10 Barry Leiba IESG state changed to IESG Evaluation from Waiting for AD Go-Ahead
2015-01-14
10 (System) IESG state changed to Waiting for AD Go-Ahead from In Last Call
2015-01-13
10 David Black Request for Last Call review by GENART Completed: On the Right Track. Reviewer: David Black.
2015-01-13
10 Gunter Van de Velde Request for Last Call review by OPSDIR Completed: Has Issues. Reviewer: David Black.
2015-01-09
10 (System) IANA Review state changed to IANA OK - No Actions Needed from IANA - Review Needed
2015-01-09
10 Pearl Liang
IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-httpbis-header-compression-10 which is currently in Last Call, and has the following comments:

We understand that this document does not contain …
IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-httpbis-header-compression-10 which is currently in Last Call, and has the following comments:

We understand that this document does not contain a standard IANA Considerations section.
After examining the draft, IANA understands that, upon approval of this document, there
are no IANA Actions that need completion.

It is helpful to have the IANA Considerations section of the document in place upon
publication for clarity purposes.


If this assessment is not accurate, please respond as soon as possible.
2015-01-02
10 Gunter Van de Velde Request for Last Call review by OPSDIR is assigned to David Black
2015-01-02
10 Gunter Van de Velde Request for Last Call review by OPSDIR is assigned to David Black
2015-01-02
10 Jean Mahoney Request for Last Call review by GENART is assigned to David Black
2015-01-02
10 Jean Mahoney Request for Last Call review by GENART is assigned to David Black
2015-01-02
10 Tero Kivinen Request for Last Call review by SECDIR is assigned to Matt Lepinski
2015-01-02
10 Tero Kivinen Request for Last Call review by SECDIR is assigned to Matt Lepinski
2014-12-31
10 Amy Vezza IANA Review state changed to IANA - Review Needed
2014-12-31
10 Amy Vezza
The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (HPACK - Header Compression for …
The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (HPACK - Header Compression for HTTP/2) to Proposed Standard


The IESG has received a request from the Hypertext Transfer Protocol WG
(httpbis) to consider the following document:
- 'HPACK - Header Compression for HTTP/2'
  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 2015-01-14. 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 specification defines HPACK, a compression format for
  efficiently representing HTTP header fields, to be used in HTTP/2.

Editorial Note (To be removed by RFC Editor)

  Discussion of this draft takes place on the HTTPBIS working group
  mailing list (ietf-http-wg@w3.org), which is archived at [1].

  Working Group information can be found at [2]; that specific to
  HTTP/2 are at [3].

  The changes in this draft are summarized in Appendix D.1.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-httpbis-header-compression/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-httpbis-header-compression/ballot/


The following IPR Declarations may be related to this I-D:

  http://datatracker.ietf.org/ipr/2506/
  http://datatracker.ietf.org/ipr/2015/



2014-12-31
10 Amy Vezza IESG state changed to In Last Call from Last Call Requested
2014-12-31
10 Amy Vezza Last call announcement was changed
2014-12-29
10 Barry Leiba Placed on agenda for telechat - 2015-01-22
2014-12-29
10 Barry Leiba Last call was requested
2014-12-29
10 Barry Leiba Last call announcement was generated
2014-12-29
10 Barry Leiba Ballot approval text was generated
2014-12-29
10 Barry Leiba IESG state changed to Last Call Requested from AD Evaluation
2014-12-18
(System) Posted related IPR disclosure: Google Inc.'s Statement about IPR related to draft-ietf-httpbis-http2-16 and draft-ietf-httpbis-header-compression-10
2014-12-17
10 Barry Leiba IESG state changed to AD Evaluation from Publication Requested
2014-12-17
10 Barry Leiba Ballot writeup was changed
2014-12-17
10 Barry Leiba
# Summary

Mark Nottingham is the Document Shepherd and Working Group Chair. Barry
Leiba is the responsible Area Director.

This specification defines HPACK, a compression …
# Summary

Mark Nottingham is the Document Shepherd and Working Group Chair. Barry
Leiba is the responsible Area Director.

This specification defines HPACK, a compression format for efficiently
representing HTTP header fields, to be used in HTTP/2.

We intend this to be published as a Proposed Standard.

# Review and Consensus

We have enjoyed active participation from a broad community, including
browser vendors, intermediaries (such as CDN and proxy vendors), server
vendors and protocol library authors; this includes both commercial
vendors and open source libraries.

Our current implementation list is at:
  https://github.com/http2/http2-spec/wiki/Implementations
 
Additionally, we have had participation and review from the
non-implementing HTTP community itself. We have substantial external
interest from the Web performance community as well.

We have also coordinated with the W3C, giving them regular updates
through the liaison and the TAG.

Process-wise, we were chartered to do this work in August 2012, with a
submission deadline of November 2014. We have treated that date
seriously, so as to bound the commitment of the developers and
implementers involved. As a result, we had a fairly high frequency of
interim meetings (six in two years), used both to discuss issues and to
hold interop events.


# Intellectual Property

The authors are currently working with their employers' respective legal
teams to update their existing disclosures, which have been brought to
the Working Group's attention.

See
for a full list of disclosures regarding this document.

# Other Points

This document has no considerations for IANA. It does not currently have an
IANA Considerations section; this will be inserted upon the next update.

IDNits reports a number of other warnings; they are all spurious.
2014-12-17
10 Barry Leiba Ballot writeup was generated
2014-12-16
10 Mark Nottingham
# Summary

Mark Nottingham is the Document Shepherd and Working Group Chair. Barry Leiba is the responsible Area Director.

This specification defines HPACK, a compression …
# Summary

Mark Nottingham is the Document Shepherd and Working Group Chair. Barry Leiba is the responsible Area Director.

This specification defines HPACK, a compression format for efficiently representing HTTP header fields, to be used in HTTP/2.

We intend this to be published as a Proposed Standard.

# Review and Consensus

We have enjoyed active participation from a broad community, including browser vendors, intermediaries (such as CDN and proxy vendors), server vendors and protocol library authors; this includes both commercial vendors and open source libraries.

Our current implementation list is at:
  https://github.com/http2/http2-spec/wiki/Implementations
 
Additionally, we have had participation and review from the non-implementing HTTP community itself. We have substantial external interest from the Web performance community as well.

We have also coordinated with the W3C, giving them regular updates through the liaison and the TAG.

Process-wise, we were chartered to do this work in August 2012, with a submission deadline of November 2014. We have treated that date seriously, so as to bound the commitment of the developers and implementers involved. As a result, we had a fairly high frequency of interim meetings (six in two years), used both to discuss issues and to hold interop events.


# Intellectual Property

The authors are currently working with their employers' respective legal teams to update their existing disclosures, which have been brought to the Working Group's attention.

See  for a full list of disclosures regarding this document.

# Other Points

Note any downward references (see RFC 3967) and whether they appear in the DOWNREF Registry (http://trac.tools.ietf.org/group/iesg/trac/wiki/DownrefRegistry), as these need to be announced during Last Call.

This document has no considerations for IANA. It does not currently have an
IANA Considerations section; this will be inserted upon the next update.

IDNits reports a number of other warnings; they are all spurious.
2014-12-16
10 Mark Nottingham State Change Notice email list changed to mnot@mnot.net, draft-ietf-httpbis-header-compression.all@tools.ietf.org, httpbis-chairs@tools.ietf.org, ietf-http-wg@w3.org
2014-12-16
10 Mark Nottingham Responsible AD changed to Barry Leiba
2014-12-16
10 Mark Nottingham IETF WG state changed to Submitted to IESG for Publication from Waiting for WG Chair Go-Ahead
2014-12-16
10 Mark Nottingham IESG state changed to Publication Requested
2014-12-16
10 Mark Nottingham IESG process started in state Publication Requested
2014-12-15
10 Mark Nottingham Changed document writeup
2014-12-15
10 Mark Nottingham IETF WG state changed to Waiting for WG Chair Go-Ahead from In WG Last Call
2014-12-15
10 Mark Nottingham This document now replaces draft-rpeon-httpbis-header-compression, draft-ruellan-headerdiff, draft-ruellan-http-header-compression instead of None
2014-12-01
10 Martin Thomson New version available: draft-ietf-httpbis-header-compression-10.txt
2014-10-07
09 Mark Nottingham Intended Status changed to Proposed Standard from None
2014-10-07
09 Mark Nottingham Changed document writeup
2014-10-07
09 Mark Nottingham Document shepherd changed to Mark Nottingham
2014-07-31
09 Mark Nottingham IETF WG state changed to In WG Last Call from WG Document
2014-07-31
09 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-09.txt
2014-06-17
08 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-08.txt
2014-04-03
07 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-07.txt
2014-02-14
06 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-06.txt
2013-12-04
05 Roberto Peon New version available: draft-ietf-httpbis-header-compression-05.txt
2013-10-21
04 Roberto Peon New version available: draft-ietf-httpbis-header-compression-04.txt
2013-08-27
03 Roberto Peon New version available: draft-ietf-httpbis-header-compression-03.txt
2013-08-21
02 Roberto Peon New version available: draft-ietf-httpbis-header-compression-02.txt
2013-07-09
01 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-01.txt
2013-06-25
00 Herve Ruellan New version available: draft-ietf-httpbis-header-compression-00.txt