A cryptographic hash function is a hash function that takes an arbitrary block of data and returns a fixed-size bit string , the cryptographic hash value , such that any ( accidental or intentional ) change to the data will ( with very high probability ) change the hash value .
A cryptographic hash function is a transformation that takes an input ( or ` message ' ) and returns a fixed-size string , which is called the hash value ( sometimes called a message digest , a digital fingerprint , a digest or a checksum ) .