On Tue, Aug 07, 2018 at 11:21:04AM +0100, Samuel Neves wrote: > > The best attack on ChaCha breaks 7 rounds, and that attack requires 2^248 > > operations. > > This number, as far as I can tell, comes from the "New features of > Latin dances" paper. There have been some minor improvements in the > intervening 10 years, e.g., [1, 2, 3, 4], which pull back the > complexity of breaking ChaCha7 down to 2^235. In any case, every > attack so far appears to hit a wall at 8 rounds, with 12 rounds---the > recommended eSTREAM round number for Salsa20---seeming to offer a > reasonable security margin, still somewhat better than that of the > AES. > > Best regards, > Samuel Neves > > [1] https://eprint.iacr.org/2015/698 > [2] https://eprint.iacr.org/2015/217 > [3] https://eprint.iacr.org/2016/1034 > [4] https://doi.org/10.1016/j.dam.2017.04.034
Thanks Samuel, I'll fix that number in the next iteration of the patchset. - Eric
