Slashdot Mirror
More MD5 Attacks Devised
rbarreira writes "Bruce Schneier's blog is reporting on a new paper by Vlastimil Klýma, which summarizes a new method for finding collisions on the MD5 hash algorithm. Furthermore, the first pair of colliding X.509 Certificates has been published by a different team."
...for copy protection of my copyrighted works. This man is doing illegal and immoral things under the DMCA, and should be stopped at once. I am willing to testify in court.
MD5 was broken for any and all purposes before
For long-term cryptographic purposes where no other form of authentication exists, yes.
As a general hashing algorithm, it works just fine.
As a short-lived authentication (probably still good for a period of several days, but for a few minutes, such as a secure website transaction, it still works perfectly well) - No need to rush out and change a few thousand storefronts just because, with luck, massive CPU power, and a week or two of CPU time, a determined cracker can fake a message. And note that I refer to signing the transaction itself, not to certs guaranteeing a site as authentic.
As an adjunct to another semi-private means of authentication (such as a password), no problem.
For checking the integrity of a file transfer - In-transit changes such as a man-in-the-middle attack, no problem. Checking an executable against the known-good hash when you have reason to suspect someone might want to change it, probably not so safe.
Now, that said, if a coder sat down today to implement a secure cryptographic hash in a new project, should they use something better, like SHA-512? Sure! But should everyone scramble to purge all references to MD5 from their existing codebases? For 99% of code out there, I'd say no.
If you can't wait for the dust to settle, use SHA-256.
But if you can, you're best off waiting a few years. This and other recent results will spark a period of frenetic research into new ways of building fast hash functions that don't have these vulnerabilities. I'm sure some great stuff will come out of it. A front-runner may not really emerge for a good few years.
I'm in some ways even more struck by Kelsey and Schneier's recent second-preimage finding attack, which works against pretty much all modern hash functions, and suggests that the fundamental Merkle-Damgard paradigm by which we build them needs to be revisited. Our hash functions may end up looking more like Panama than like MD4.
Xenu loves you!