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Re: [TLS] Deprecating more (DSA?) (was Re: Deprecating RC4 (was: draft-ietf-tls-encrypt-then-mac))

Hanno Böck <hanno@hboeck.de> Tue, 15 April 2014 19:03 UTC

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Date: Tue, 15 Apr 2014 21:02:55 +0200
From: Hanno Böck <hanno@hboeck.de>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
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Subject: Re: [TLS] Deprecating more (DSA?) (was Re: Deprecating RC4 (was: draft-ietf-tls-encrypt-then-mac))
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On Tue, 15 Apr 2014 14:15:11 -0400
Daniel Kahn Gillmor <dkg@fifthhorseman.net> wrote:

> On 04/15/2014 10:03 AM, Hanno Böck wrote:
> > My opinion on that is that we should have multiple lines of defense.
> > Sure, if the RNG is bad we should fix it. But we all know good RNGs
> > is a nontrivial problem. So while fixing RNGs is a priority, we
> > also should have algorithms that don't completely break so badly
> > that they spit out the public key if the RNG fails.
> 
> https://tools.ietf.org/html/rfc6979 suggests a way to use DSA that
> doesn't break as catastrophically if the RNG fails.

Interesting, didn't know that.

But basically, the whole discussion about DSA's security is missing the
point. It's probably possible to implement DSA in a secure way. But
what I really want to achieve is getting TLS simpler.
I think there's wide agreement that DSA if done correctly has a
security comparable to RSA. However, in TLS everyone uses RSA, nobody
uses DSA.
And I think unused code is dangerous. Because nobody cares, nobody
tests it, nobody looks at it but it still can bite you when it comes to
security. That I think is a lesson we should've learned from
Heartbleed. And therefore I think we should identify unused parts of
the TLS spec and deprecate it.

-- 
Hanno Böck
http://hboeck.de/

mail/jabber: hanno@hboeck.de
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