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RE: #466 segment compression

From: <K.Morgan@iaea.org>
Date: Tue, 29 Apr 2014 08:41:59 +0000
To: <matthew@kerwin.net.au>, <ietf-http-wg@w3.org>
CC: <martin.thomson@gmail.com>
Message-ID: <0356EBBE092D394F9291DA01E8D28EC20112984BB2@sem001pd.sg.iaea.org>
I think the simplest idea is to require the origin to separate attacker-controlled data and private/confidential data by segments.  All of the rest of the intermediary problems go away since an intermediary already can’t re-frame across segment boundaries, plus it allows an intermediary to do whatever it wants within a segment (compress/uncompress/concatenate/de-compress+re-compress).

The thing I like about Martin’s idea to switch to one compression context per segment is that it provides greater compatibility between HTTP/1.x T-E and HTTP/2 transfer codings.  Per-frame compression as we have it now is compatible with T-E when going from 2 -> 1.x, but it’s not compatible from 1.x -> 2.  The added complexity and the “vast increase in DoS surface area” [1] is a big deal though.

[1] https://github.com/http2/http2-spec/issues/466#issuecomment-41361711




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Keith S. Morgan
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From: phluid61@gmail.com [mailto:phluid61@gmail.com] On Behalf Of matthew@kerwin.net.au
Sent: Tuesday,29 April 2014 08:53
To: ietf-http-wg@w3.org
Cc: Martin Thomson
Subject: Re: #466 segment compression

Sorry for replying to myself.

On 29 April 2014 16:26, Matthew Kerwin <matthew@kerwin.net.au<mailto:matthew@kerwin.net.au>> wrote:
All three operations (determining frame length, compressing frames, and padding) are hop-by-hop operations, and any intermediary can second-guess or obstinately undo the previous hop's choices if it wants.


​I just noticed the ​bit in 10.6 that says that intermediaries can't add compression. Is that the delineation to which you referred in #466 Martin?  That text introduces complexity I hadn't imagined when proposing per-frame compression. I'll think about it some more.


--
  Matthew Kerwin
  http://matthew.kerwin.net.au/


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Received on Tuesday, 29 April 2014 08:42:38 UTC

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