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Security enhancement for A5/1 without losing hardware efficiency in future mobile systems

Komninos, N. & Honary, B. (2002). Security enhancement for A5/1 without losing hardware efficiency in future mobile systems. Paper presented at the 3rd IEE International Conference on 3G Mobile Communication Technologies, 8 - 10 May 2002, London.


A5/1 is the strong encryption algorithm which protects the air interface of the GSM cellular network. However, in the Fast Software Encryption Workshop 2000 two attacks, the biased birthday attack and the random subgraph attack against A5/1 were presented [1]. In this paper, we propose new security enhancements to improve A5/1 encryption algorithm from the biased birthday attack [1] and random subgraph attack [3] [4] in order to be used in future mobile communication systems. The improvements that make both attacks impractical are based on the clocking mechanism of the registers, and their key setup routine. Furthermore, we have increased the linear complexity of A5/1 to make the solution of the linear equations [2] impractical in real time systems. Finally, both original and modified versions of A5/1 were implemented easily in a CPLD device for 3rd generation mobile systems.

Publication Type: Conference or Workshop Item (Paper)
Additional Information: © 2002 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.
Subjects: Q Science > QA Mathematics > QA76 Computer software
Departments: School of Science & Technology > Computer Science > Software Reliability
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