Stream ciphers for GSM networks

With the advance of wireless communications technology, mobile communicatio ns has become more convenient than ever. However, because of the openness o f wireless communications, how to protect the privacy between communicating parties is becoming a very important issue. In this paper, we focus on the security of transferring voice message on the Global System for Mobile com munication (GSM) networks. Stream cipher is recommended for message encrypt ion and decryption. First, a key generator is presented. Then, on the basis of the key generator, stream ciphers are designed with respect to differen t levels of securities of GSM networks. Simulation results indicate that th e key generator always produces key strings of evenly distributed 0's and 1 's and with a very long period; i.e. it is very unlikely that repeated patt erns will appear. Cryptanalysis and operational analysis show that the prop osed stream ciphers are secure and efficient; consequently, they provide a comprehensive set of message encryption/decryption algorithms for GSM netwo rks. (C) 2001 Elsevier Science B.V. All rights reserved.