Re: [Cfrg] Chopping out curves
Adam Back <adam@cypherspace.org> Fri, 17 January 2014 12:42 UTC
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Date: Fri, 17 Jan 2014 13:41:59 +0100
From: Adam Back <adam@cypherspace.org>
To: Alyssa Rowan <akr@akr.io>
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Cc: Adam Back <adam@cypherspace.org>, cfrg@irtf.org
Subject: Re: [Cfrg] Chopping out curves
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I'm not sure if we should be going as far as generating new curves, or significantly tweaking choices in the existing curves in incompatible ways (eg new generators), I thought original idea was more to provide in RFC format the best rigid/NUMs curves available that people are already starting to use so they at least have a reference. Generating new curves or significantly deviating from them or their exiting parameter choices, creates our own NUMs risk, and a restart on the review process, creates something that needs to have its own (maybe derivative) name, and places CFRG in the biased editorial position of both generating & selecting... Adam On Fri, Jan 17, 2014 at 07:41:53AM +0000, Alyssa Rowan wrote: >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA512 > >On 17/01/2014 02:36, Adam Back wrote: > >> Uh I meant the Curve25519 and Curve3617. > >We have three key sizes for AES, and three hash sizes with SHA-2 and >SHA-3 (and the candidates). > >I propose: >• curve25519 (plus twist t25519) >• curve3617 >• e521 > >That gives us three curves with strength roughly congruent to the 128, >192 and 256 key sizes, and about as good performance as we're going to >get for those levels. > >curve25519 is likely to be used for high-performance ECDH; its twist >is likely to be used for high-performance encryption and signing. > >curve3617 seems likely to be used for higher-assurance encryption and >signing (Silent Circle intends to use it, for one). > >e521 is slower, but very conservative - maybe you'd want to use it for >very careful signatures or encryption; the prime field is of course a >well-known Mersenne prime people are already used to (thanks to >secp521r1), and it's so rigid, three people came up with the >parameters independently. > >I wouldn't cry a river if we dropped e521 from that list. > >Those are, I think, the two or three that applications are most likely >to actually want to use in practice. > > >Regarding the t25519 basepoint, the argument for using the ed25519 >basepoint is that it's already out there and thus already rigid, but >yes, it is ugly. > >If you do choose a new basepoint, Watson (and I can see the sense in >that), please rigidly document the choice criteria so the decision can >be independently verified and confirmed (minimal y, right?). > >I haven't had my first cup of tea yet today, so I apologise if I'm >wrong, but I believe any new basepoint would need to go through the >SafeCurve verification tests again, because ℓ would change? - run it >yourself for sanity checking, and please post the source files on the >list so we can use Sage or something to verify it too, but please also >speak to Tanja and djb about that to get wider verification. > >- -- >/akr >-----BEGIN PGP SIGNATURE----- > >iQIcBAEBCgAGBQJS2N7AAAoJEOyEjtkWi2t6OaUQAIyZsJdPlguckuHKMY+UdCJN >YEaRx4MXQ5BrBH2Z8HrMdrY+4mmNqogI23MzAUYjE5/TdKcQvfOYDtpW7D6ooKAx >K+SFj553BmE6By4F3woZ/5bsRH3oifnFaT7g6OMRijGpkaN//AWIx8PdMU3LbrrB >tXHG2ciEmlKr5rdve8EhA3c9dUZo3XE2qltiWplaK5kObskl+bpXibm0JmajMVzl >DLi0b5lzh3l7JZVqL0gR1Nk/swd5PSXqgET2k7NhBfrP0+NbJ7niGYUFT1gVtxVz >2Qg0aDusvlRTeFeVCxUiZV7oDQg1+JbaMxTUg6gAP6HuUCnuzy2A6D+0Dt9qajX2 >UvHezZawZhC8PL2XPIgjXhTVCiUCz6oexy1V2OCKFO+ZIGcvypIMT6N5WbVZVzIb >G4YNv+IrUEFnfssfkueXr4huBat4gZ2HXArG4hWd/85EOvxbTng4tAkShSRJl5bS >cYaej5Tlz5WC4evzZC+VvnHeyzVInPn9AFJdkKjQeuPgXaANeluI9SdpFW5hY3w4 >o6wmLDdnX2lxVeq8rY0pz0aXvxTm/IFpn7SlVs7RZU0upmuCzquKfAUgcjcaYaj0 >JkLPu8Iq/aSpfIF4foC7jNJn43yNN76rqpxUjXICQosbg3ybqZTzs+ppjB10SPOr >n8JoVsmG08Boh8FpVHo2 >=8vwB >-----END PGP SIGNATURE----- >_______________________________________________ >Cfrg mailing list >Cfrg@irtf.org >http://www.irtf.org/mailman/listinfo/cfrg
- [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Trevor Perrin
- Re: [Cfrg] Chopping out curves Michael Hamburg
- Re: [Cfrg] Chopping out curves Dan Harkins
- Re: [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Michael Hamburg
- Re: [Cfrg] Chopping out curves Adam Back
- Re: [Cfrg] Chopping out curves Adam Back
- Re: [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Alyssa Rowan
- Re: [Cfrg] Chopping out curves David McGrew
- Re: [Cfrg] Chopping out curves Adam Back
- Re: [Cfrg] Chopping out curves Alyssa Rowan
- Re: [Cfrg] Chopping out curves Robert Ransom
- Re: [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Manuel Pégourié-Gonnard
- Re: [Cfrg] Chopping out curves Alyssa Rowan
- Re: [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Igoe, Kevin M.
- Re: [Cfrg] Chopping out curves Manuel Pégourié-Gonnard
- Re: [Cfrg] Chopping out curves Watson Ladd
- Re: [Cfrg] Chopping out curves Mike Hamburg
- Re: [Cfrg] Chopping out curves Manuel Pégourié-Gonnard
- Re: [Cfrg] Chopping out curves Jon Callas