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A cryptographic hash function (CHF) is a mathematical algorithm that maps data of arbitrary size (often called the "message") to a bit array of a fixed size (the "hash value", "hash", or "message digest") It is a one-way function, that is, a function which is practically infeasible to invert Ideally, the only way to find a message that produces a given hash is to attempt a brute-force search of possible inputs to see if they produce a match, or use a rainbow table of matched hashes Cryptographic hash functions are a basic tool of modern cryptographyThe ideal cryptographic hash function has the following main properties: it is deterministic, meaning that the same message always results in the same hash it is quick to compute the hash value for any given message it is infeasible to generate a message that yields a given hash value it is infeasible to find two different messages with the same hash value a small change to a message should change the hash value so extensively that the new hash value appears uncorrelated with the old hash value (avalanche effect)Cryptographic hash functions have many information-security applications, notably in digital signatures, message authentication codes (MACs), and other forms of authentication

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