Re: [TLS] WGLC for "Deprecating TLSv1.0 and TLSv1.1"

"Martin Thomson" <mt@lowentropy.net> Thu, 09 May 2019 06:41 UTC

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Date: Thu, 09 May 2019 02:41:15 -0400
From: "Martin Thomson" <mt@lowentropy.net>
To: tls@ietf.org
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Archived-At: <https://mailarchive.ietf.org/arch/msg/tls/P9lczgZKH3EZJnFE0yGERaa53Tk>
Subject: Re: [TLS] WGLC for "Deprecating TLSv1.0 and TLSv1.1"
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On Thu, May 9, 2019, at 16:09, Peter Gutmann wrote:
> You could just say "use SHA-2", which covers the whole family.  Now in
> practice "SHA-2" means "SHA-256" so it'll be the same as saying SHA-256
> directly, but the more generic SHA-2 leaves it open to interpretation for the
> three people who use something other than SHA-256.

Though I don't think we'll see it happen any time soon, I don't think we want to completely close the door on new hash functions.  SHA-3 might be dead, but that doesn't mean we won't eventually be motivated to move to another one.

>From memory, we see a non-trivial amount of SHA-384, though that might just be in its pairing with AES-256-GCM.  It's routinely paired with P-384, which we do get a little bit of.  We even have P-521 in quantities large enough that we can't turn it off, which is likely paired with SHA-512.