Thanks for the article Nakul.

I have a question about HASHBYTES (and hashing in general) to which I have found it impossible so far to find a definite answer. Perhaps you know: you list HASHBYTES as providing change detection, but is that really true?

In a lot of places you see claims that "any change" will affect the hash value but that is not true: it is easy to see that for any (finite) hash algorithm there are always two files (or datablobs) that are the same size and differ by only two bits and that will give the same hash value. But it is not so obvious (at least to me) if there can be two files/datablobs that differ by only one bit and that will have the same hash value. Of course I realise that from a practical point of view it is extremely unlikely that any two files/datablobs will have the same hash value but I am interested in the theoretical question: will a single bit change always change the hash value?

Thanks,

Alex