[waynecochran]

Are you worried about hash collisions from different objects? The probability of a collision of N distinct objects with SHA-1 is (N choose 2) * 1 / 2^161. For a trillion objects the probability is about 1.7 x 10^-25. I think we can safely write code without collisions until the sun goes super novae.

[mrlonglong]

It's not that I'm worried about, it's the fact malicious files can be crafted for a particular hash that could replace the original.