Re: Encryption simplification

Julian Reschke <julian.reschke@gmx.de> Sun, 30 October 2016 10:39 UTC

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To: Martin Thomson <martin.thomson@gmail.com>, HTTP Working Group <ietf-http-wg@w3.org>
References: <CABkgnnWVB3mnkGn9OmvgmLU7yDww40OQ_0pp_HeNdziqGYA0og@mail.gmail.com>
From: Julian Reschke <julian.reschke@gmx.de>
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Date: Sun, 30 Oct 2016 11:35:01 +0100
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Subject: Re: Encryption simplification
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On 2016-10-30 11:22, Martin Thomson wrote:
> After discussion about content codings, I've made something of a
> drastic change to the encryption draft.  A preview is here:
>     http://httpwg.org/http-extensions/encryption-preview.html
>
> The pull request is here:
>     https://github.com/httpwg/http-extensions/pull/252
>
> This is a huge simplification in many ways, so I think that's a fair
> improvement.
>
> The main assertion that this assumes is this: content codings should
> be self-descriptive.
>
> Obviously, this isn't a strong assertion given that this content
> coding requires a key, and SDCH relies on having an external
> dictionary, but the point is that the contents of the message can be
> decoded without reading additional header fields.  This is consistent
> with the observation that James Manger made about the MICE content
> coding previously [1].
>
> To that end, I've removed the Encryption header field and packed the
> critical data into the content itself.  This is more efficient and
> avoids strange cross-header-field correlation between Encryption and
> Content-Encoding.  It retains Crypto-Key and key identifiers, but
> that's necessary since they generally travel separately.
>
> I realize that we're close to the draft submission deadline, so I'm
> planning to publish the draft with these modifications.  We can
> continue to have this discussion.  Thanks to the magic of revision
> control systems, it's easy to revert this change if needed.
>
> (Yes, this messes with webpush, I still need to talk to people about
> what to do there.)
>
>
> [1] https://lists.w3.org/Archives/Public/ietf-http-wg/2016AprJun/0242.html

+1 in general.

That said, doesn't have Crypto-Key a similar problem (in that you might 
not now what applied encryption content codings it applies to)?

Best regards, Julian