Re: [TLS] sect571r1

Dave Garrett <> Thu, 16 July 2015 02:42 UTC

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From: Dave Garrett <>
To:, Dan Brown <>
Date: Wed, 15 Jul 2015 22:42:54 -0400
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Subject: Re: [TLS] sect571r1
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On Wednesday, July 15, 2015 09:42:51 pm Dan Brown wrote:
> What about sect571k1, a Koblitz curve, aka NIST curve K-571? (By the way it has no unexplained constants...). Has it been removed already, or does the question also refer K-571 too?

Already dropped. That's obviously not irreversible, but it's unambiguously in the virtually unused camp. The initial goal was to drop all largely unused curves.

This question is just about sect571r1, which is far closer to secp384r1 & secp521r1 in terms of usage, though still notably less. If you want to argue for going with sect571k1 and not sect571r1, I don't think the WG is on-board with that. Even if we continued to allow it, I doubt much would add support for it to be worthwhile.

The scan I linked to found one; literally a single server on the entire Internet, that actually supports sect571k1 for ECDHE. The stats also show 1575 "support" it, so I'm not sure what's going on there specifically. (if someone can explain this bit of those stats, please do)