PRVHASH is a hash function that generates a uniform pseudo-random number sequence derived from the message. PRVHASH is conceptually similar (in the sense of using a pseudo-random number sequence as a hash) to keccak and RadioGatun schemes, but is a completely different implementation of such concept. PRVHASH is both a "randomness extractor" and an "extendable-output function" (XOF), however the resulting hashes have security level that corresponds to the hash length specification: the collision resistance is equal to 2^(n/2) while the preimage resistance is equal to 2^n, where n is the resulting hash length in bits.