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Re: [TLS] Confirming Consensus on removing RSA key Transport from TLS 1.3

Hanno Böck <hanno@hboeck.de> Thu, 27 March 2014 08:56 UTC

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Date: Thu, 27 Mar 2014 09:55:27 +0100
From: Hanno Böck <hanno@hboeck.de>
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Subject: Re: [TLS] Confirming Consensus on removing RSA key Transport from TLS 1.3
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On Wed, 26 Mar 2014 22:12:19 +0100 (CET)
mrex@sap.com (Martin Rex) wrote:

> DHE has the problem that it lacks a required set of parameters.
> Generating everything anew and having to verify all parameters
> on the client side for each and every handshake is prohibitively
> expensive, so a number of implementations seem to be using a static
> keypair for the server that is manually generated by an admin once,
> and never refreshed/ updated, making it appear better than static
> RSA, but de-facto much worse.

Appart from the other issues, I think it would make a lot of sense to
change DHE handling in TLS 1.3 away from "server can have arbitrary
parameters".
The authors of the triple handshake attack have proposed having a set
of "known good" parameters and I think this is the way to go for TLS
1.3 and DHE. It's probably enough to say "we define a 2048 and a 4096
DH parameter set with tested and known primes" and allow the option to
easily define more if there ever is a need to say "we need 8192 bit DHE
now".

-- 
Hanno Böck
http://hboeck.de/

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