Message Authentication Codes (MACs)

A Message Authentication Code (MAC), also known as a cryptographic checksum or a keyed hash function, is widely used in practice. In terms of security functionality, MACs share some properties with digital signatures, since they also provide message integrity and message authentication. However, unlike digital signatures, MACs are symmetric-key schemes and they do not provide nonrepudiation. One advantage of MACs is that they are much faster than digital signatures since they are based on either block ciphers or hash functions.