Hi exon,
> One approach to take when brute-forcing passwords could be to simply add
> random bytes to a stream until it collides and then using a
> collision-generator to generate a collision short enough to not be
> discarded by the password validation mechanism. Those with deeper
> insights into the MD5 algorithm could probably come up with which bytes
> to add to make it collide faster, but it still means brute-forcing an
> MD5 password of considerable length is down from months to mere hours.
Interesting idea. If a cracker actually cared about the *real* password
that the user chose, then this might be useful. If he just cared about
*a* password that makes the hash, it is irrelevant though.
> All this is ofcourse theory. I don't know enough cryptography to
> determine what is possible and what isn't, but since SHA1 hasn't been
> broken (yet) and there are enough open and free implementations of it to
> go around I'm a bit surprised to find that MD5 is considered for use in
> new applications.
Um... You didn't get the news about SHA1?
http://www.schneier.com/blog/archives/2005/08/new_cryptanalyt.html
It's definately broken. It'll take a few years before people can do it
as quickly as they can with MD5, and I don't know of any tools people
have written, but don't rely on it either for collision resistance.
tim
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Received on Jan 07 2006
Intro
