3 ms·
What evidence do you have for the terabytes claim? Not saying you're incorrect, but I'm unfamiliar with any literature that suggests that.
by _asummers 11y ago
What evidence do you have for the terabytes claim? Not saying you're incorrect, but I'm unfamiliar with any literature that suggests that.
- cjbprime 11y agoIf there is another input that SHAs to the same commit hash, it's not going to be as small, and it's not going to look like a standard patch. I'm not sure "terabytes" is justified either, but the point's a good one.
- espadrine 11y agoLike I said, finding a SHA-1 second-preimage attack is vastly more difficult than finding a SHA-1 preimage attack. You can claim to have found one as soon as you have any means that is not brute-force which produces a colliding preimage, no matter how practical it is (ie, it could require the use of humanity's entire energy spending for a thousand years, and more disk space than can be built with the Earth's atoms). In theory, nothing I know forbids the possibility of finding an algorithm which yields a 160-bit solution within a few years. In practice, such an algorithm is tremendously more difficult (and potentially impossible) to find than simply finding a SHA-1 second-preimage attack, which is already vastly more difficult to find than a preimage attack, which is also vastly more difficult than getting a non-bruteforce collision. It would certainly be a phenomenal achievement, however. We still don't have a practical preimage attack on MD5, 10 years after the first actual collision found… Regardless, we're only now beating the first challenge after 20 years. It is likely to take more to go from there to a second-preimage attack, and more still to have it be a 160-bit solution within a practical amount of time. git will double its lifetime multiple times before then. Something shinier will have replaced it.