[Cfrg] Is draft-agl-cfrgcurve-00 incompatible with Ed25519?

Tony Arcieri <bascule@gmail.com> Fri, 09 January 2015 23:11 UTC

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From: Tony Arcieri <bascule@gmail.com>
Date: Fri, 09 Jan 2015 15:10:37 -0800
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Subject: [Cfrg] Is draft-agl-cfrgcurve-00 incompatible with Ed25519?
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It would be good to get a definitive answer on this question before
draft-agl-cfrgcurve-00 adopted (which I'm guessing is likely to happen)

For clarity: I like draft-agl-cfrgcurve-00 and I hope it does get adopted.
I would simply like the CFRG to have the option to adopt Ed25519 in the
future. I am not necessarily saying the CFRG *should* adopt Ed25519
wholesale. However I would like for the CFRG to specifically address this
question in advance in anticipation of it coming up in the future.

If Ed25519 is incompatible with draft-agl-cfrgcurve-00, I would suggest
that drafg-agl-cfrgcurve-00 be specifically amended to include the
possibility of using Ed25519 for signatures in the future.

Ed25519 is already being deployed in SSH and OpenPGP contexts, so I hope
the CFRG would not accidentally rule it out in the name of "compromise".
Having similar-but-incompatible Edwards curves used in different protocol
contexts sounds like a recipe for disaster.

Tony Arcieri