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Block Cipher Modes

A block cipher mode, or mode, for short, is an algorithm that features the use of a symmetric key block cipher algorithm to provide an information service, such as confidentiality or authentication.

Currently, NIST has approved fourteen modes of the approved block ciphers in a series of special publications. As summarized on the Current Modes page, there are eight confidentiality modes (ECB, CBC, OFB, CFB, CTR, XTS-AES, FF1, and FF3), one authentication mode (CMAC), and five combined modes for confidentiality and authentication (CCM, GCM, KW, KWP, and TKW).

Several other modes have been submitted to NIST for consideration; the submission documents are available at the Modes Development page. NIST welcomes public input on whether to approve any of these modes. Comments may be submitted to