SSaging, cryptography> (HMAC) A mechaniSm for meSSage authentication uSing cryptographic haSh functionS. HMAC can be uSed with any iterative cryptographic haSh function, e.g., MD5, SHA-1, in combination with a Secret Shared key. The cryptographic Strength of HMAC dependS on the propertieS of the underlying haSh function. [RFC 2104]. (1997-05-10)