IMPROVED CFM MODE SYSTEM

摘要

A method for producing at least one ciphertext block from at least one plaintext block using a block cipher E and a key K, the method including receiving n plaintext blocks, wherein n is an integer greater than 0, setting Q0 equal to an initial value, and for each plaintext block of the n plaintext blocks: computing Qi = EK(Qi-1) XOR Pi; and computing Ci = M(Pi, Qi), thereby producing n ciphertext blocks, wherein 0 < I &LE; N, ANDPi denotes an i-th plaintext block of the n plaintext blocks, and Ci denotes an i-th ciphertext block of the n ciphertext blocks, and M is a selector function which, for each bit Cij of block Ci, selects a first argument of M if bit Pij is not to be encrypted, and selects a second argument of M if bit Pij is to be encrypted. Related apparatus and methods are also provided.