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Enhancement of A5/1 Stream Cipher Overcoming its Weakneses

Authors:
Mahdi Madani
Salim Chitroub

Keywords: GSM Networks; Stream Cipher; Mobile Security; Encryption and Cryptography; Cryptanalysis; Non-Linear Boolean Functions; Linear Feedback Shift Gegister.

Abstract:
The Global system for Mobile (GSM) communication is still the most widely used cellular system in the world, with over the billion customers around the world; even the fourth and fifth generations are now operated in some countries. However, GSM bears numerous security vulnerabilities and for that reason it has seriously considered security threats. Although GSMs architecture is designed in such a way to provide various security features like authentication, data and signaling confidentiality, and the user secrecy, the GSM channel is yet susceptible to replaying, interleaving and man-in-the-middle attacks. The GSM voice calls are encrypting a family of algorithms collectively called A5. A5/1 is the stream cipher which encrypts the information transmitted from a mobile user. Initially, A5 algorithm was kept secret to ensure the security, but us algorithm was disclosed many cryptanalytic attacks that have made in evidence the weakness of A5 algorithm. In this paper, after the discussion on the A5/1 encryption algorithm, and the attacks that it has suffered, we will put in evidence the weakness of A5/1. Although attacks that can be used to break the A5/1 algorithm require incredible computing power so that not only certain people with certain computer could break the A5/1 algorithm, however, this does not preclude the necessity of improve safety A5/1. We propose here to enhance the A5/1 stream cipher by overcoming its weakness.

Pages: 154 to 159

Copyright: Copyright (c) IARIA, 2014

Publication date: June 22, 2014

Published in: conference

ISSN: 2308-4219

ISBN: 978-1-61208-347-6

Location: Seville, Spain

Dates: from June 22, 2014 to June 26, 2014