Re: [boost] [hash2] Question about cryptographic guarantees of hash_append_unordered_range

On 8 Dec 2024, at 23:19, Peter Dimov via Boost wrote: Vinnie Falco wrote:

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On Sun, Dec 8, 2024 at 11:27 AM Ivan Matek via Boost wrote:

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...sum is commutative. Bitwise XOR and modular unsigned multiplication are also commutative.

Bitwise xor has the problem that xoring two equal values yields 0, so the sequences [1], [1, 1, 1], [1, 2, 2] and so on all hash to the same thing.

And addition gives the same result for [3] , [2,1], [1,1,1] etc. My guess is that a hash of an unordered set is probably impossible to make crypto-safe. But maybe with modular exponentiation? Cheers, Kostas