Cryptographic Hash Functions

A cryptographic hash function is a hash function which is considered practically impossible to invert, that is, to recreate the input data from its hash value alone. The input data is often called the message, and the hash value is often called the message digest or simply the digest.

The ideal cryptographic hash function has four main properties:

  • it is easy to compute the hash value for any given message
  • it is infeasible to generate a message that has a given hash
  • it is infeasible to modify a message without changing the hash
  • it is infeasible to find two different messages with the same hash

Cryptographic hash functions have

many information security applications, notably in digital signaturesmessage authentication codes (MACs), and other forms of authentication. They can also be used as ordinary hash functions, to index data in hash tables, for fingerprinting, to detect duplicate data or uniquely identify files, and

as checksums to detect accidental data corruption. Indeed, in information security contexts, cryptographic

hash values are sometimes called (digitalfingerprintschecksums, or just hash values.

At CRG, research on time complexity of hash functions and use of hash functions for compression is being conducted by the group members.