[TLS] Deprecating TLS 1.0, 1.1 and SHA1 signature algorithms

Kurt Roeckx <kurt@roeckx.be> Mon, 11 January 2016 18:30 UTC

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Date: Mon, 11 Jan 2016 19:30:17 +0100
From: Kurt Roeckx <kurt@roeckx.be>
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Subject: [TLS] Deprecating TLS 1.0, 1.1 and SHA1 signature algorithms
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Hi,

After the SLOTH paper, we should think about starting to deprecate
TLS 1.0 and TLS 1.1 and the SHA1 based signature algorithms in TLS
1.2.

As I understand it, they estimate that both TLS 1.2 with SHA1 and
TLS 1.0 and 1.1 with MD5|SHA1 currently require about 2^77 to be
broken.  They all depend on the chosen prefix collision on SHA1,
with the MD5 part in TLS 1.0 and 1.1 not adding much.

It seems that disabling SHA1 in TLS 1.2 doesn't buy you anything
unless you also disable TLS 1.0 and 1.1.


Kurt