Re: [TLS] consensus on backwards compatibility changes

Florian Weimer <fweimer@redhat.com> Thu, 29 January 2015 10:02 UTC

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Date: Thu, 29 Jan 2015 11:01:57 +0100
From: Florian Weimer <fweimer@redhat.com>
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Subject: Re: [TLS] consensus on backwards compatibility changes
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On 01/28/2015 09:42 PM, Martin Rex wrote:
> There are several serious design flaws (resulting in serious weaknesses)
> in the TLSv1.2 signature algorithm extension, however.  TLSv1.2 is the
> only TLS protocol version where (rsa,md5) is a valid signature algorithm
> for creating "digitally-signed" PDUs (ServerKeyExchange and
> CertificateVerify), and that was a terribly stupid decision.
> Even (rsa,sha1) is significantly weaker than what every prior TLS
> protocol version, including SSLv3 had been using (rsa,sha1+md5).

Yes, that's what I meant, or more precisely, the {rsa,sha1} default in
case of a missing TLS extension (which includes SSLv2 Client Hello case).

-- 
Florian Weimer / Red Hat Product Security