What is Message authentication code MAC?

Understanding Message authentication code MAC

A small block of data that is generated using a secret key and then appended to the message used to address integrity. A MAC is a cryptographic checksum generated from a message and a secret key allowing recipients with the same key to verify both data integrity and authenticity. Unlike digital signatures MACs use symmetric keys and dont provide non-repudiation. Common MAC algorithms include HMAC CMAC and GMAC. MAC usage is specified in standards like FIPS 198 HMAC NIST SP 800-38B and ISO/IEC 9797. Organizations implement MACs to protect message integrity in communications file transfers stored data and cryptographic protocols. For example a financial application might calculate and attach HMACs to all transaction messages allowing recipients to verify that transaction details havent been altered during transmission and originated from a legitimate source possessing the shared secret key. Related terms HMAC Integrity Cryptography Symmetric key Digital signature Data authentication Cryptographic hash function.