Hello On Wed, Jul 04, 2007 at 10:38:26AM +0100, Dave Cridland wrote: > (FWIW, Ian's mention of a "one hour attack" is a collision attack, not a > preimage attack, and finds a pair of two-block messages which collide, both > of which have specific properties, and the time figures are quoted for an > IBM P690, which is somewhat bigger iron than I have about, anyway. Our > attacker needs a selected preimage attack, and will almost certainly need > one where the legitimate message is several blocks long for MD5, and their > primary source of computing power is likely to be a distributed botnet at > best - I'm not clear if this attack is distributable or not, but I'm not > concerned by it).
Not sure what attack he mentioned, but there is collision project. Collisions in time of minutes on PC, and there is something about generating a colliding data with some prefix if I understand it well (there was something it can generate data that has given MD5 and with some initial hash state or so). http://cryptography.hyperlink.cz/MD5_collisions.html Not that I would understand it much, nor read it properly, just that the author is from the same country as me, so I heard about it. So I think if you have few hours or days, you have no much problems in finding something, if you know how. -- The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system Michal 'vorner' Vaner
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