Re: [TLS] Another IRINA bug in TLS

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Wed, 20 May 2015 14:59 UTC

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Date: Wed, 20 May 2015 17:59:26 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Watson Ladd <watsonbladd@gmail.com>
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Subject: Re: [TLS] Another IRINA bug in TLS
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On Wed, May 20, 2015 at 10:05:25AM -0400, Watson Ladd wrote:
> https://weakdh.org/
> 
> Transcript hashing will solve this problem.

AFAICT, extended_master_secret won't save you from this.

The problem is screwed up server key PoP, and EMS will not fix that
(TLS 1.3 does).

Also, this is not the first attack arising from the way server key
PoP is done...

BTW: Client key PoP is not screwed, so attacker can't forward client
certs...

> In the meantime, you want to turn off DH_EXPORT.

Only works on serverside...

> There are also implications for false start.

I have regarded using false start with non-named groups (and
thus without key checks) as a bad idea.



-Ilari