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Re: [hybi] On TLS-only Approaches

John Tamplin <jat@google.com> Mon, 23 August 2010 04:30 UTC

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From: John Tamplin <jat@google.com>
Date: Mon, 23 Aug 2010 00:30:06 -0400
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To: Adam Barth <ietf@adambarth.com>
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Subject: Re: [hybi] On TLS-only Approaches
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On Mon, Aug 23, 2010 at 12:13 AM, Adam Barth <ietf@adambarth.com> wrote:

> I should probably let EKR respond here, but I'll ask anyway.  What
> does the message overhead look like for the null cipher spec?  We
> don't necessarily need to use a non-null cipher spec for ws even if we
> use a TLS handshake (of course, we need a reasonable cipher spec for
> wss).


It looks to me, according to openssl ciphers, the only NULL cipher supported
is AECDH-NULL-SHA which still does SHA1 for integrity protection, so I
assume it would have the same overhead.  RFC4346 seems to indicate a
TLS_NULL_WITH_NULL_NULL CipherSuite option which would have a 0-byte MAC, so
presumably you would only pay the 5-byte record overhead and there would be
no padding.  That is more reasonable, but still seems large considering we
have been arguing over a few bytes in the framing.

-- 
John A. Tamplin
Software Engineer (GWT), Google

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