Extended Authentication Technique
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
A method is disclosed which extends the technique of block chaining with ciphertext feedback, referred to as cipher block chaining (CBC), to provide a single output which may be utilized for three different functions, namely, as an output chaining value (OCV), for message i which can be used as the initial chaining value (ICV) for message i+l, as a message authentication code (MAC) to be appended to a clear or enciphered message (M) for transmission from a sender to a receiver, or as the compressed encoding of a message (CE(M)) for signature verification purposes. AB In the figure is the basic technique of CBC for the message M=Xl, X2 ....Xn, where each X is an eight-byte data block.