One-key MAC
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"CMAC" redirects here. For other uses, see CMAC (disambiguation).
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.[1] The preferred name is now "OMAC2".[2]
- The OMAC1 refinement,[2] which became an NIST recommendation in May 2005 under the name CMAC.[3]
OMAC is free for all uses: it is not covered by any patents.[4]