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[TLS] DSA should die

Hanno Böck <hanno@hboeck.de> Wed, 01 April 2015 18:12 UTC

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Date: Wed, 01 Apr 2015 20:12:21 +0200
From: Hanno Böck <hanno@hboeck.de>
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Subject: [TLS] DSA should die
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Hi,

Mozilla just removed DSA support from Firefox. It seems the use of
(non-ecc) DSA in TLS is pretty much nonexistent. Still the TLS 1.3 draft
contains DSA.

Proposal: DSA should go away and not be part of TLS 1.3.

Reasons to remove DSA:
* DSA with 1024 bit is considered weak and DSA with more than 1024 bit
  is widely unsupported.
* DSA has comparable security to RSA (it using same keysize) which is
  the de-facto-default. Given that everybody uses RSA and nobody uses
  DSA having the latter only adds unneccessary complexity.
* DSA can fail badly with bad random number generators.

Some numbers:
In the 2013 https ecosystem scan there were 17 DSA keys on public IPs,
none of them CA-trusted:
http://conferences.sigcomm.org/imc/2013/papers/imc257-durumericAemb.pdf

I think it's safe to say nobody will care if DSA is removed.

cu,
-- 
Hanno Böck
http://hboeck.de/

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