Wednesday, February 16, 2005

Oops. Is SHA-1 broken?

Schneier reports that a Chinese team has broken SHA-1. It appears that he's seen their (not yet public) paper and while he can't yet tell whether the attack is real notes that the paper is by a reputable team and appears to assume that it's for real.

How broken remains to be seen: a reduction from 2^80 to 2^69 hash operations to brute force it still appears to me to leave a very large problem for an adversary to solve, but it does mean that (s)he can solve it 2048 times as fast.

Scary.