> > Raimo, if people believe that hash(A)=hash(B) implies A=B, so strong
> > > believe, that they use it in their programs, > > > > It's a matter of engineering. Usually that is good enough. > > > > If you don't think it's good enough then you should probably also worry > > about how often strcmp(a, b) returns 0 when strings a and b don't match. > > No, that is not good enough, that is not good, that is very bad. The > probability of A=B under the condition hash(A)=hash(B) is close > to zero, not to one as Marc Espie & Co are telling here. > > In practical terms, if I rsync a file from X to Y, and rsync says it is complete, how to verify the 4G files actually are equal? Given that rsync only knows that hash(A) was equal to hash(B) at the end, what do you propose to use for verification? -- May the most significant bit of your life be positive.
