Chunked Oblivious HTTP Messages
draft-ietf-ohai-chunked-ohttp-06

IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-ohai-chunked-ohttp-06. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there is a single action which we must complete.

In the message namespace of the Media Types registry located at:

https://www.iana.org/assignments/media-types/

two new media types are to be registered as follows:

Name: ohttp-chunked-req
Template: [ TBD-at-Registration ]
Reference: [ RFC-to-be ]

Name: ohttp-chunked-res
Template: [ TBD-at-Registration ]
Reference: [ RFC-to-be ]

We understand that this is the only action 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.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Sr. Specialist

The following Last Call announcement was sent out (ends 2025-10-06):

From: The IESG
To: IETF-Announce
CC: draft-ietf-ohai-chunked-ohttp@ietf.org, mbishop@evequefou.be, ohai-chairs@ietf.org, ohai@ietf.org, shivankaulsahib@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Chunked Oblivious HTTP Messages) to Proposed Standard


The IESG has received a request from the Oblivious HTTP Application
Intermediation WG (ohai) to consider the following document: - 'Chunked
Oblivious HTTP Messages'
  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
last-call@ietf.org mailing lists by 2025-10-06. 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 document defines a variant of the Oblivious HTTP message format
  that allows chunks of requests and responses to be encrypted and
  decrypted before the entire request or response is processed.  This
  allows incremental processing of Oblivious HTTP messages, which is
  particularly useful for handling large messages or systems that
  process messages slowly.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-ohai-chunked-ohttp/



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


The document contains these normative downward references.
See RFC 3967 for additional information:
    draft-irtf-cfrg-aead-limits: Usage Limits on AEAD Algorithms (None - Internet Research Task Force (IRTF) stream)

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?
 
  The consensus for this document is broad and solid. Multiple active WG participants voiced support during WGLC. No objections were raised during WGLC. There was clear consensus, existing deployments and no objections.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?
 
  The WG discussed applicability and use-cases for chunked OHTTP early on, given that chunking changes the security and privacy properties of OHTTP while not providing the guarantees of a proxied TLS connection. Specifically, there were concerns about the lack of forward secrecy and replay protection as well as how interactivity introduced by chunking potentially enables timing attacks. The authors addressed these concerns by adding an [Applicability section](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-applicability) and adding text on [interactivity](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-interactivity-and-privacy), [forward secrecy](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#section-7) and [replay attack risk](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-message-truncation).
 
  There was also discussion of the [incremental nature of HTTP](https://github.com/ietf-wg-ohai/draft-ohai-chunked-ohttp/issues/19), motivating use of an HTTP "Incremental" header to get incremental forwarding. The draft now references the ["Incremental" HTTP header field](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-incremental-00) draft which has been adopted by the HTTP WG.

3. 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.)
 
  None indicated on the list; no threats of appeal recorded. As mentioned above, there were initial concerns about the privacy impact and use-cases for chunked OHTTP but they were resolved through discussion during meetings and [issue discussion](https://github.com/ietf-wg-ohai/draft-ohai-chunked-ohttp/issues?q=is%3Aissue%20state%3Aclosed). WGLC feedback was supportive.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?
 
  There are several existing deployments and implementations of Chunked OHTTP. [Cloudflare reported](https://mailarchive.ietf.org/arch/msg/ohai/xygArMZVfrSDtYvINHhYZHSGK1Q/) deployed implementations of both gateway and relay. [Apple also](https://datatracker.ietf.org/doc/minutes-120-ohai-202407260130/) has deployments of Chunked OHTTP for Private Cloud Compute and related AI features. There is an implementation by Microsoft for their [attested OHTTP server](https://github.com/microsoft/attested-ohttp-server). Google's QUICHE has support for [chunked OHTTP](https://quiche.googlesource.com/quiche.git/%2B/d71d77ba2b251b5b3fa049e8475c62ba1d473157).

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.
 
  The document interacts with HTTP and has new Media Types. Authors requested a [media-types review](https://mailarchive.ietf.org/arch/msg/media-types/voY6mqv9c5LQGM2odHIoqFlUbuU/) for two new media types. The "Incremental HTTP Messages" work is being done in HTTP WG and is cited as a normative reference. The chairs also sent a pointer to the Chunked OHTTP draft's last call to the HTTP WG mailing list; there's a large overlap in the people involved between the two groups.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
 
  Media-type review requested for message/ohttp-chunked-req and message/ohttp-chunked-res. No other formal expert reviews (MIB/YANG/URI) are applicable.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?
 
  N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.
 
  N/A

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?
 
  Yes. The draft is clearly needed and is deployed and already being used by millions of users. The text is clear and complete.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?
   
    Chunked OHTTP interacts with the Security and HTTP areas. There have been extensive discussions about both, as mentioned above, primarily because there is large overlap between the participants. Formal SECDIR and HTTPDIR review should still occur.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?
   
    Proposed Standard, because it involves multiple parties (client, relay, gateway) implementing a commonly-understood protocol. Yes, the datatracker reflects that intent.


12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.
   
    The authors have confirmed that no IPR exists to their knowledge.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.
   
    Yes.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
   
    There is a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to proceed soon.
   
    There is also a downref to a CFRG document, RFC 9180 (HPKE), but this RFC is listed in the [DOWNREF registry](https://datatracker.ietf.org/doc/downref/).
   
    There is 1 warning for "non-ascii characters in the document", and line 584 appears to be too long. These are minor formatting issues which are pending a draft update.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].
   
    No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?
   
    None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.
   
    There is a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to progress soon.
   
    RFC 9180 is listed in the DOWNREF registry.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?
   
    The draft references the [Incremental HTTP header field](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-incremental-00). There are no pending issues for this draft and it is expected to progress soon. There is also a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to progress soon.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.
   
    None. The draft does not obsolete, update, or down-grade any RFCs.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).
   
    The IANA considerations section looks accurate.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.
   
    N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?
 
  The consensus for this document is broad and solid. Multiple active WG participants voiced support during WGLC. No objections were raised during WGLC. There was clear consensus, existing deployments and no objections.

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?
 
  The WG discussed applicability and use-cases for chunked OHTTP early on, given that chunking changes the security and privacy properties of OHTTP while not providing the guarantees of a proxied TLS connection. Specifically, there were concerns about the lack of forward secrecy and replay protection as well as how interactivity introduced by chunking potentially enables timing attacks. The authors addressed these concerns by adding an [Applicability section](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-applicability) and adding text on [interactivity](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-interactivity-and-privacy), [forward secrecy](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#section-7) and [replay attack risk](https://datatracker.ietf.org/doc/html/draft-ietf-ohai-chunked-ohttp-06#name-message-truncation).
 
  There was also discussion of the [incremental nature of HTTP](https://github.com/ietf-wg-ohai/draft-ohai-chunked-ohttp/issues/19), motivating use of an HTTP "Incremental" header to get incremental forwarding. The draft now references the ["Incremental" HTTP header field](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-incremental-00) draft which has been adopted by the HTTP WG.

3. 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.)
 
  None indicated on the list; no threats of appeal recorded. As mentioned above, there were initial concerns about the privacy impact and use-cases for chunked OHTTP but they were resolved through discussion during meetings and [issue discussion](https://github.com/ietf-wg-ohai/draft-ohai-chunked-ohttp/issues?q=is%3Aissue%20state%3Aclosed). WGLC feedback was supportive.

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?
 
  There are several existing deployments and implementations of Chunked OHTTP. [Cloudflare reported](https://mailarchive.ietf.org/arch/msg/ohai/xygArMZVfrSDtYvINHhYZHSGK1Q/) deployed implementations of both gateway and relay. [Apple also](https://datatracker.ietf.org/doc/minutes-120-ohai-202407260130/) has deployments of Chunked OHTTP for Private Cloud Compute and related AI features. There is an implementation by Microsoft for their [attested OHTTP server](https://github.com/microsoft/attested-ohttp-server). Google's QUICHE has support for [chunked OHTTP](https://quiche.googlesource.com/quiche.git/%2B/d71d77ba2b251b5b3fa049e8475c62ba1d473157).

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.
 
  The document interacts with HTTP and has new Media Types. Authors requested a [media-types review](https://mailarchive.ietf.org/arch/msg/media-types/voY6mqv9c5LQGM2odHIoqFlUbuU/) for two new media types. The "Incremental HTTP Messages" work is being done in HTTP WG and is cited as a normative reference. The chairs also sent a pointer to the Chunked OHTTP draft's last call to the HTTP WG mailing list; there's a large overlap in the people involved between the two groups.

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
 
  Media-type review requested for message/ohttp-chunked-req and message/ohttp-chunked-res. No other formal expert reviews (MIB/YANG/URI) are applicable.

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?
 
  N/A

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.
 
  N/A

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?
 
  Yes. The draft is clearly needed and is deployed and already being used by millions of users. The text is clear and complete.

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?
   
    Chunked OHTTP interacts with the Security and HTTP areas. There have been extensive discussions about both, as mentioned above, primarily because there is large overlap between the participants. Formal SECDIR and HTTPDIR review should still occur.

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?
   
    Proposed Standard, because it involves multiple parties (client, relay, gateway) implementing a commonly-understood protocol. Yes, the datatracker reflects that intent.


12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.
   
    The authors have confirmed that no IPR exists to their knowledge.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.
   
    Yes.

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)
   
    There is a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to proceed soon.
   
    There is also a downref to a CFRG document, RFC 9180 (HPKE), but this RFC is listed in the [DOWNREF registry](https://datatracker.ietf.org/doc/downref/).
   
    There is 1 warning for "non-ascii characters in the document", and line 584 appears to be too long. These are minor formatting issues which are pending a draft update.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].
   
    No.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?
   
    None.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.
   
    There is a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to progress soon.
   
    RFC 9180 is listed in the DOWNREF registry.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?
   
    The draft references the [Incremental HTTP header field](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-incremental-00). There are no pending issues for this draft and it is expected to progress soon. There is also a normative reference to an in-progress CFRG draft, [draft-irtf-cfrg-aead-limits-10](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-aead-limits-10). This document is in Research Group Last Call, and is expected to progress soon.

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.
   
    None. The draft does not obsolete, update, or down-grade any RFCs.

20. 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 aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).
   
    The IANA considerations section looks accurate.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.
   
    N/A

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/