3 ms·
Hurrah! Curves that have a cofactor of 1. (One of the things I didn't like about DJB's speed hacked curve25519…) Since they share the same field as the NIST c
by nullc 13y ago
Hurrah! Curves that have a cofactor of 1. (One of the things I didn't like about DJB's speed hacked curve25519…)
Since they share the same field as the NIST curves it also means that software won't need any other code for these.
I do wish they'd strengthened their verifyably random practices beyond the brainpool technique, instead of just complaining about it. :)
For example, they took their non-public nothing up my sleeve choice (C), then hashed it (H(C)) and announced H(C) and this procedure to the world, then put H(C) in a Bitcoin transaction and took M to be the block hash of the block 100 after the block confirming it (because it takes 2^66 sha256 operations to retry a single Bitcoin block if you don't like its outcome, and 100 after ensures that there would be a race with the public network), then picked their random seed as HMAC(M||next-week's NIST random beacon,C) you'd have a random value who's selection someone could only compromise by either inverting H() or controlling the announcing team, and controlling the NIST beacon, and doing 2^66 sha256 * the number of retries on that step (or compromising sha256 to make bitcoin mining trivial).
- mti 13y agoSomeone interested in a serious, rather than derisive, attempt at selecting good curves with cofactor 1 may want to look at the recent paper by Bos, Costello, Longa and Naehrig[0]. [0]: http://eprint.iacr.org/2014/130 http://eprint.iacr.org/2014/130
- FiloSottile 13y agoMmmmh, that's a cool scheme, but how does that buy you more than using cos(1) as they did with BADA55-VPR-224? The point I believe is that you still need to retry until you find a "safe curve" and they found the BADA55-VPR-224 A tweaking that. Or am I missing something that made it easier?