Re: [TLS] New drafts: adding input to the TLS master secret

Eric Rescorla <ekr@networkresonance.com> Tue, 09 February 2010 04:49 UTC

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Date: Mon, 08 Feb 2010 20:52:12 -0800
From: Eric Rescorla <ekr@networkresonance.com>
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Cc: paul.hoffman@vpnc.org, tls@ietf.org
Subject: Re: [TLS] New drafts: adding input to the TLS master secret
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At Mon, 08 Feb 2010 19:27:01 -0800,
Eric Rescorla wrote:
> In general, if you have an acceptable amount of entropy you
> don't need to worry about leaking PRNG output. If you don't
> you really don't have any business doing TLS.

This wasn't well phrased. If you're a TLS server and you
just do static RSA, then it is safe to do TLS even without
a good source of entropy. On the other hand, if you're doing
DHE or you're a TLS client doing static RSA, then it's pretty
hard to have a secure system unless you can muster enough
entropy to make exhaustive search of the entropy space
imdeasible.

-Ekr