[Iburinoc]

While that is true, part of the contents that is hashed is the time of commit. Therefore if you (somehow...) managed to get that hash, you could just reset and commit again. Or amend.

In any case, I believe he was joking. The odds of a sha1 collision are very very low.

[sytelus]

Very low indeed. Chance of SHA1 collision is of the order of 2^52. One person explained it this way: Chance of everyone currently on Earth winning a jackpot in their lifetime is actually higher than a single random SHA1 collision. It should be actually mind boggling how many of the software systems and algorithms rely on hashes and them being not collided.

[yuhong]

I think it is 2^61 now, the paper that once showed the 2^52 attack has removed the claims.