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Does a (cryptographic?) function satisfying these 3 constraints exist?

Posted 5 months ago
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  1. f(program,state)=hash. hash is unique for every pair of (program,state). f, program and state are public. Maybe state can be made private.

  2. f^−1(hash) does not exist, and there is no function g, g(hash)=(program,state). Meaning, there is no other way to obtain the hash but by using f.

  3. verify(program,state,hash)=true, if f(program,state)=hash. False otherwise.

2 Replies
Posted 5 months ago

Wouldn't any cryptographic hash work?

f[program_, state_] := Hash[program <> state, "SHA512", "HexString"];
verify[program_, state_, hash_] := f[program, state] == hash;

hash = f["Hello", "World"]
verify["Hello", "World", hash]
(* True *)

Rohit is right. Another option, you can use HMAC

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