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Re: [TLS] TLS v1.2 performance (was Re: TLSv1.2 with DSA client cert and

Peter Gutmann <pgut001@cs.auckland.ac.nz> Sat, 19 February 2011 02:15 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: nmav@gnutls.org, tls@ietf.org
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Date: Sat, 19 Feb 2011 15:16:06 +1300
Subject: Re: [TLS] TLS v1.2 performance (was Re: TLSv1.2 with DSA client cert and
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Nikos Mavrogiannopoulos <nmav@gnutls.org> writes:

>This is also not easy to fix in TLS 1.3. Even if TLS 1.3 only requires to
>hold the state of a single hash, implementations must be prepared to hold the
>entire state just in case TLS 1.2 is negotiated.

But you know at the first message whether you're going to continue with TLS
1.2 or 1.3.  If you only start the hashing after the first handshake packet
then you only need to use the one hash that both sides have agreed on.  Heck,
you can even fix it right now with an extension (which is what my code does
iff it finds another copy of my code at the other end).

>That was a bad design decision in TLS 1.2 (if we assume that not caching all
>messages was a requirement).

Can I say "I toldja so" now?

Peter.

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