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by klodolph 3420 days ago
That is not a very precise way of describing the uniformity of hash functions, and it's not actually true. For example, if my input has some element with 50% probability, then the hashed output is going to have some element with at least 50% probability.

But this is well-known, and because it's well-known, no sane cryptographic system cares that hash outputs leak information that way. For example, look at PBKDF2, HMAC, or various asymmetric key authentication schemes.
1 comments
danbruc 3420 days ago
You are right, I did not correctly word what I wanted to say. I was not thinking about repeated messages, I was only thinking about subsets of all possible messages. Say you are hashing HTML documents, then all your inputs will be in the subspace having <!DOCTYPE html><html as first characters but that information will be erased by the hash function.
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