Speech Scrambling Employing Lorenz Fractional Order Chaotic System

Qassim Kadhim, Jaafar; K. M. AlAzawi, Maher

	Speech Scrambling Employing Lorenz Fractional Order Chaotic System
Journal of Engineering and Sustainable Development
Article 1, Volume 17, Issue 4, 2013, Pages 195-211
Authors
Jaafar Qassim Kadhim; Maher K. M. AlAzawi
Abstract
This paper presents techniques of speech scrambling based-fractional order chaotic system which is used due to many properties; first of all using fractional order as key will increase key space which makes it is very difficult to decrypt by a 3d-party. It is a random like noise behavior; it is defined over continuous number fields, which leads to possibility of using many nonlinear functions in encryption. A one channel with chaotic masking is used to encrypt low level speech signal. The low level speech signal problem is solved by using two-channel secure communication. In a two channel method, one channel is used for transmitting a pure driving signal to achieve faster synchronization while a highly nonlinear function is used to encrypt the speech signal and transmit it in the other channel. The simulation results show that scrambled speech is unintelligible, preserving bandwidth, the dynamic response of fractional order chaotic system is highly sensitive to fractional order values and the variation of a parameter, chaotic trajectory is very unpredictable, key space is expanded and guaranteed higher security. The results show that, the speech scrambling based fractional order chaotic system is highly secure compared with classical speech scrambling techniques. Some security measures are used for comparison.
Keywords
Speech Scrambling; Fractional Order Chaotic System; synchronization

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