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Re: [TLS] New Version Notification for draft-putman-tls-preshared-ecdh-00.txt

Tony Putman <Tony.Putman@dyson.com> Fri, 01 December 2017 08:49 UTC

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From: Tony Putman <Tony.Putman@dyson.com>
To: Katriel Cohn-Gordon <me@katriel.co.uk>
CC: "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] New Version Notification for draft-putman-tls-preshared-ecdh-00.txt
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Date: Fri, 01 Dec 2017 08:49:32 +0000
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Subject: Re: [TLS] New Version Notification for draft-putman-tls-preshared-ecdh-00.txt
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From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Katriel Cohn-Gordon
> If you add the fourth (static-static) DH, you should be protected
> against poor generation of ephemeral keys.

Thanks, this sounds like a good idea. It can be precomputed (and stored if
all comms is to a single server) so it doesn't slow down the actual protocol
exchange. 

I added the two static public keys into the premaster calculation as they are
included in the Session Id definition in [Kudla]. I wonder if I can replace them
with the static-static computation, which seems (to me) to offer the same
protection.
-- 
Tony


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