Message Authentication Codes

We observed that hash functions could only provide a strong degree of data integrity if combined with other security mechanisms that protect the hash value from being manipulated. One such method is introducing a key into generating a ‘hash.’ Of course, this means we are no longer dealing with a ‘hash function.’

This section discusses MACs. These are symmetric cryptographic primitives designed to provide data origin authentication, which, as we mentioned, is a stronger notion than data integrity. This is one of the most commonly encountered mechanisms for data origin authentication (data integrity) and the most common symmetric technique.