Computer Security Resource Center

Computer Security Resource Center

Computer Security
Resource Center

Block Cipher Techniques

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

Created January 04, 2017, Updated February 12, 2018