Patent ID: 7343011

Claim:
A method, comprising: converting a message to a sequence of message words using a message padder; generating a first message integrity codeword, L, and a second message integrity codeword, R, based on the message words and respective first authentication key, K 0 , and second authentication key, K 1 , the generating based on operations comprising modulo 2 sum, modulo 2 B sum, bit rotation, and block transformation, where B is a positive integer, wherein generating comprises setting the second message integrity codeword, R, equal to the modulo 2 sum of the second message integrity codeword, R, plus the first message integrity codeword, L, after being rotated left 17 bits; and transmitting a cyphertext message based on the first and second message integrity codewords and the message words over a communications medium to a receiver.