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

Marsh Ray <marsh@extendedsubset.com> Sat, 19 February 2011 05:20 UTC

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Date: Fri, 18 Feb 2011 23:21:14 -0600
From: Marsh Ray <marsh@extendedsubset.com>
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To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
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Subject: Re: [TLS] TLS v1.2 performance (was Re: TLSv1.2 with DSA client cert and
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On 02/18/2011 08:12 PM, Peter Gutmann wrote:
>
> you either have to cache all
> handshake messages or run multiple hashes in parallel until you know which one
> you need to settle on.  Either option leads to performance suckage.

It seems like the bulk of the data in a handshake is in the certs, 
mostly sent by the server.

So one server-side optimization might be to buffer all the handshake 
messages /except/ the server's fixed certs. You can make a guess from 
the most common hashes and run one or two in parallel. You could 
reconstruct the full handshake data if you guess wrong.

More unfortunate complexity. :-(

It's ironic to the point of being sub-optimal that endpoints are 
expected to bear the cost of running multiple hashes over the data - 
just to then throw away half the results.

I saw somewhere NIST just standardized truncated SHA-512 variants. Isn't 
choice wonderful?

- Marsh

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