The literature discusses several variants of the CFB mode. There is the one described in NIST Special Publication 800-38A which requires that messages are a multiple of the feed back size, and there is the so-called "ISO variant of CFB" which works with arbitrary message sizes. The latter is described in the "Handbook of Applied Cryptography". There may be others.
Which variant is implemented in Crypto++? It seems that CFB_Mode<AES> accepts messages of arbitrary size, hence this doesn't seem to be the FIPS variant, is it the ISO variant? Whatever variant it is, does it at least behave identically to the FIPS variant (from the 800-38A document) when the message size is a multiple of the feed back size? Joachim -- work: [EMAIL PROTECTED] (http://www.netacquire.com) private: [EMAIL PROTECTED] (http://www.kraut.ca)
