Keyed hashing method for message authentication. HMAC is used with an iterative cryptographic hash function, such as MD5 or SHA-1, in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying hash function.
Hash Message Authentication Code. A mechanism for ensuring the data integrity of online communications that uses cryptographic message digest functions to provide online integrity checking of data that is transmitted. HMAC can be used with any iterative cryptographic message digest function, for example, MD5, SHA-1, in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying message digest function. HMAC is also called Hash-based Message Authentication Code algorithm. See also message digest; message digest function.
Hashed Message Authentication Code. (Hashed MAC.) A standardized approach to using hash algorithms to create message authentication codes. HMAC is generally a pair of nested digests: the first is a digest the key and the data; the second is a digest of the key and the output of the first digest.