Last Call Review of draft-ietf-httpbis-encryption-encoding-08
review-ietf-httpbis-encryption-encoding-08-secdir-lc-sparks-2017-04-05-00

Request Review of draft-ietf-httpbis-encryption-encoding
Requested rev. no specific revision (document currently at 09)
Type Last Call Review
Team Security Area Directorate (secdir)
Deadline 2017-04-06
Requested 2017-03-23
Other Reviews Opsdir Last Call review of -08 by Al Morton (diff)
Genart Last Call review of -08 by Pete Resnick (diff)
Review State Completed
Reviewer Robert Sparks
Review review-ietf-httpbis-encryption-encoding-08-secdir-lc-sparks-2017-04-05
Posted at https://mailarchive.ietf.org/arch/msg/secdir/UIgNGCzv3J9Ls2px7XQxkd5Wgn4
Reviewed rev. 08 (document currently at 09)
Review result Ready
Draft last updated 2017-04-05
Review completed: 2017-04-05

Review
review-ietf-httpbis-encryption-encoding-08-secdir-lc-sparks-2017-04-05

I have reviewed this document as part of the security directorate's
ongoing effort to review all IETF documents being processed by the
IESG.  These comments were written primarily for the benefit of the
security area directors.  Document editors and WG chairs should treat
these comments just like any other last call comments.

Document : draft-ietf-httpbis-encryption-encoding-08

Summary: This document is ready for publication as Proposed Standard (except perhaps for one recommendation)

This document defines a content encoding for encrypting the contents of an HTTP message that
facilitates storing the encrypted contents and decrypting the content for rendering incrementally
(before the full content is received). The draft is clear, and implementation should be straightforward.
It's security considerations section is detailed.

I did not verify the math that went into the provided examples.

My only concern is that the document suggests it would be ok to use a counter to provide a unique salt value
for each message. I suspect that provides the kind of information leak the draft discusses avoiding.

I also pointed out a couple of nits to the editor, and those are addressed already in his working copy (on github).