Patent ID: 6377687
Filing Date: 2002-04-23
Classification: H04L,H04W

Abstract:
A method of forward enhanced CMEA cryptoprocessing for each message in a call, for use in a CMEA encryption system employed in a wireless telephone system comprising the steps of:introducing an unprocessed message; creating one or more secret offsets; performing a transformation on the unprocessed message to produce a transformed message; performing an iteration of a CMEA process on the transformed message to produce an intermediate ciphertext message, the iteration of the CMEA process employing an enhanced tbox function using an involutary lookup, the tbox function receiving inputs, the inputs to the enhanced tbox function being subjected to a permutation using one or more of the secret offsets to produce a permutation result; and performing an inverse transformation on the intermediate ciphertext message to produce a final processed message.