Patrick Useldinger wrote:
David Eppstein wrote:
When I've been talking about hashes, I've been assuming very strong cryptographic hashes, good enough that you can trust equal results to really be equal without having to verify by a comparison.
I am not an expert in this field. All I know is that MD5 and SHA1 can create collisions. Are there stronger algorithms that do not? And, more importantly, has it been *proved* that they do not?
I'm not an expert either, but I seem to remember reading recently that, while it's been proven that it's possible for SHA1 to have collisions, no actual collisions have been found. Even if that's not completely correct, you're *far* more likely to be killed by a meteorite than to stumble across a SHA1 collision. Heck, I'd expect that it's more likely for civilization to be destroyed by a dinosaur-killer-sized meteor.
With very few exceptions, if you're contorting yourself to avoid SHA1 hash collisions, then you should also be wearing meteor-proof (and lightning-proof) armor everywhere you go. (Those few exceptions would be cases where a malicious attacker stands to gain enough from constructing a single hash collision to make it worthwhile to invest a *large* number of petaflops of processing power.) Sure it's not "100% perfect", but... how perfect do you *really* need?
Jeff Shannon
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