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Re: [TLS] New cached-info draft 09 posted

Marsh Ray <marsh@extendedsubset.com> Tue, 13 July 2010 15:21 UTC

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Date: Tue, 13 Jul 2010 10:21:23 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: Stefan Santesson <stefan@aaa-sec.com>
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Subject: Re: [TLS] New cached-info draft 09 posted
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On 07/13/2010 09:27 AM, Stefan Santesson wrote:
> Marsh,
>
> I would rather fix the issue with the following updated text:
>
> "The hash algorithm used to calculate hash values SHALL be the Finished
> message hash algorithm of the handshake exchange from which the hashed
> information was cached. The Finished message hash algorithm in this context
> is the hash algorithm used to hash handshake messages in the calculation of
> verify_data (i.e. Hash(handshake_messages) as defined in section 7.4.9 of
> RFC 5246)."
>
> I see no reason to involve the PRF function here. It only adds unnecessary
> complexity as far as I can see.

Is this intended to be a TLS 1.2-only feature?

If not, how is it to be interpreted for 1.0 and 1.1? They don't use this 
"Hash(handshake_messages)" definition because the unified hash mechanism 
was introduced in 1.2.

To me, the PRF seems simpler because it's consistently defined in each 
TLS version.

- Marsh

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