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Re: [hybi] deflate-stream and masking

Greg Wilkins <gregw@intalio.com> Mon, 20 June 2011 08:21 UTC

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Date: Mon, 20 Jun 2011 18:21:04 +1000
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From: Greg Wilkins <gregw@intalio.com>
To: "Andy Green (林安廸)" <andy@warmcat.com>
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Cc: Hybi <hybi@ietf.org>
Subject: Re: [hybi] deflate-stream and masking
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On 20 June 2011 18:11, "Andy Green (林安廸)" <andy@warmcat.com> wrote:
> On 06/20/2011 07:33 AM, Somebody in the thread at some point said:
>
> Hi -
>
>> As an unmasked WS stream, it was 50675 bytes, and as a masked stream
>> is was 52623 bytes.
>> I then compressed both these streams with gzip and got 13306 bytes for
>> unmasked and 51704 bytes for the masked!!!!
>>
>> So for this very typical example, masking was sufficiently random to
>> completely negate the benefits of compression.
>
> Isn't this just saying that it's dumb to mask-then-compress?
>
> You could just compress-then-mask and get the 13Kbyte result directly and
> "safely".

That is exactly what I'm saying!

We should use a deflate-frame extension that does compress-then-mask,
rather than a deflate-stream "extension" that does mask-then-compress.

cheers

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