On Mon, 9 Sep 2013 14:18:41 +0300 Alexander Klimov <alser...@inbox.ru> wrote: > On Sun, 8 Sep 2013, Perry E. Metzger wrote: > > What's the current state of the art of attacks against AES? Is the > > advice that AES-128 is (slightly) more secure than AES-256, at > > least in theory, still current? > > I am not sure what is the exact attack you are talking about, but I > guess you misunderstood the result that says: "the attack works > against AES-256, but not against AES-128" as meaning that AES-128 > is more secure. It can be the case that to break AES-128 the attack > needs 2^240 time, while to break AES-256 it needs 2^250 time. Here > AES-128 is not technically broken, since 2^240 > 2^128, but AES-256 > is broken, since 2^250 < 2^256, OTOH, AES-256 is still more secure > against the attack. >
There is a related key attack against AES-256 that breaks it in order 2^99.5, far worse than 2^250! However, several people seem to have assured me (in private email) that they think such related key attacks are not important in practice. Perry -- Perry E. Metzger pe...@piermont.com _______________________________________________ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography