CMAC

One-key MAC (OMAC) is a family of message authentication codes constructed from a block cipher much like the CBC-MAC algorithm. It may be used to provide assurance of the authenticity and, hence, the integrity of data. Two versions are defined: The original OMAC of February 2003, which is seldom used. The preferred name is now "OMAC2". The OMAC1 refinement, which became an NIST recommendation in May 2005 under the name CMAC. OMAC is free for all uses: it is not covered by any patents.