عنوان البحث(Papers / Research Title)
Determination of complexity of pseudo-random
الناشر \ المحرر \ الكاتب (Author / Editor / Publisher)
ستار بدر سدخان المالكي
Citation Information
ستار,بدر,سدخان,المالكي ,Determination of complexity of pseudo-random , Time 6/12/2011 6:35:56 AM : كلية تكنولوجيا المعلومات
وصف الابستركت (Abstract)
Determination of complexity of pseudo-random
الوصف الكامل (Full Abstract)
Determination of complexity of pseudo-randomsequence based on Z-transform
SATTAR BADER SADKHAN (*),RAGHAD KADHIM SALIH (**)
SUMMARY. –
In recent years, stream cipher systems have played a big role especially in computer networks. Stream cipher systems depend on pseudo-random (PR) binary key sequences which are mixed with the plaintexts using addition with modulo two to produce the ciphertexts. The PR key sequences are characterized by three properties which defi ne the measure of security for these sequences. These properties are period, complexity and randomness. There are several methods to determine the degree of complexity of these PR sequences like Berlekamp-Massey method, atricestechniques, and using software computing techniques (Neural Networks, Fuzzy Logic and GeneticAlgorithms). This paper presents a proposed method to determine the degree of complexity of these PR sequences using one of the properties of the Z-transform which is periodic sequence property. This proposed method enable us to compute the degree of complexity of any periodic sequence produced from linear or nonlinear generators and accurate results are obtained. The steps of the proposed procedure are given, two different examples are illustrated, one of them for a PR equence over GF(2), and the second example for PR sequence over GF(5).
Key words: Stream cipher, Pseudo random sequence, complexity evaluation, Z-transform.
INTRODUCTION:-
Cryptography and information security are considered as one of important sciences in the world, especially after using the wide spread use of computersin many world wide applications. The need to keep certain messages secret has been appreciated for thousands of years. The idea of a cipher system is to disguise confi dential information in such a way that its meaning is unintelligible to an unauthorized person. The information to be concealed is called plaintext, while the resulted information is called ciphertext (1).(*) University of Babylon, IRAQ; e-mail: drengsattar@ieee.org(**) Department of Applied Sciences, University of Technology, Babylon, IRAQ
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