On Thu, 17 Feb 2005, Jason Holt wrote: > Unfortunately, neither of these gives as much protection as we'd hope. > Recent research suggests that collisions on the concatenation of hashes are > much easier to find than naive brute force would suggest, and the Kaminsky > paper shows that you actually have quite a lot of flexibility in where you put > the "garbage" which causes a collision. He came up with two different mp3 > files which play just fine but have different contents. > > Weird, huh?
I think the Tripwire example is a good thought experiment for "what effect could this possible have on me?" One can easily imagine a bash script, a few lines long, that "does something bad". If someone can find a collision between some random garbage prepended with this nasty bash script, and some frequently executed Linux binary, then Tripwire (or other programs that check for modification based on a hash) will be none the wiser. Additionally, only a single person (perhaps even someone with access to a supercomputer) has to find that collision one time, and then that Evile Program can be distributed to ub3rh4x0rs around the world. I think if you look at something like MD5 or SHA-1 being "broken", even as barely as they've been broken now, and can't find Evile and Nasty things to exploit, you just lack a healthy imagination ;-) ~ Ross -------------------- BYU Unix Users Group http://uug.byu.edu/ The opinions expressed in this message are the responsibility of their author. They are not endorsed by BYU, the BYU CS Department or BYU-UUG. ___________________________________________________________________ List Info: http://uug.byu.edu/cgi-bin/mailman/listinfo/uug-list
