Processo para determinar uma chave para embaralhar tráfego rádio-telefônico entre um terminal rádio-telefônico e uma rede rádio-telefônica e terminal rádio-telefônico para embralhar sinais entre terminais rádio-telefônicos e uma rede rádio-telefônica

摘要

A method and apparatus is presented for transforming a key variable used for scrambling cellular data traffic between a terminal and a network in alternate ways using information transmitted to the terminal from the network with which the terminal is connected. Transformation is accomplished by passing portions of the key variable through a series of S-boxes which provide a mapping between the input and output. Moreover, it is disclosed how to save memory by iteratively passing portions of the key variable through the same S-box.