In cryptography, a message authentication code (MAC) is a short piece of information used to authenticate a message. A MAC algorithm (sometimes termed a keyed hash function) accepts as input a secret key as well as the message, and produces a MAC (sometimes known as a tag). The MAC protects both a message's integrity—by ensuring that a different MAC will be produced if the message has changed—as well as its authenticity—because only someone who knows the secret key could have generated a valid MAC.
MAC algorithms can be constructed from other cryptographic primitives, such as cryptographic hash functions (as in the case of HMAC) or from block cipher algorithms (OMAC and PMAC).
See also
- Data Authentication Code , a DES-based MAC algorithm from ANSI.
- UMAC
- HMAC
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