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Pseudorandom Permutation

Definition

A pseudorandom permutation is a deterministic algorithm that transforms an input data block into an output block of identical size, appearing as a random permutation to an observer without the secret key. It functions as a reversible mapping, meaning the original input can be accurately recovered from the output using the same key. These functions are central to block ciphers, providing robust cryptographic scrambling properties. The resulting output sequence exhibits statistical properties closely resembling truly random permutations.