Hash Tools Hash messages or files

A cryptographic hash function (CHF) is a mathematical algorithm that maps data of arbitrary size (often called the "message") to a bit string of a fixed size (the "hash value", "hash", or "message digest") and is a one-way function, that is, a function which is practically infeasible to invert.

The 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