المجلة الدولية للعلوم والتقنية

Hence, GSM security is needed to provide the user of a network with anonymity and privacy when making a call and to ensure that the network operator bills the correct customer and to make sure that the operators don't interfere with each other either unintentionally or intentionally. Therefore it is highly important that reasonable technologically security measure are needed to be done to ensure the privacy of the user's phone calls, text messages and data, and to prevent unauthorized user to use of the service Many algorithms are used for making the GSM secure. A3, A5 and A8 are the main algorithms used for the security in mobile networks. Algorithm A3 is used for authentication, A5 is used for encryption, and A8 is used for the generation of a cipher key k_c . The paper points out that the security level in GSM system can be enriched by improving the scheme of A3 algorithm. Proposed scheme is implemented at some level and analyzed thoroughly to show that the proposed scheme provides better security in the GSM network. The proposed A3 algorithm is simulated by using MATLAB Software. In this paper, encryption is presented in the Authentication phase during the A3 algorithm.