Report on the Second Modes of Operation Workshop (August 2001)

Morris Dworkin, a mathematician from NIST’s Computer Security Division, served as the moderator of the workshop. He welcomed the attendees and introduced the other participants from NIST: Bill Burr, Elaine Barker, Aaron Nelson, and, at the registration table, Vickie Harris and Teresa Vicente. He reviewed the three current Federal Information Processing Standards (FIPS) that establish block cipher modes of operation. FIPS 81 specifies four confidentiality modes for use with the Data Encryption Standard (DES) as the underlying block cipher: the Electronic Codebook (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), and Output Feedback (OFB) modes. FIPS 113 specified an authentication mode of the DES that is essentially the Cipher Block Chaining-Message Authentication Code (CBC-MAC) mode; this mode was also discussed in an appendix of FIPS 81. FIPS 46-3 approved the seven modes of operation of Triple DES that are specified in ANSI X9.52.