Speech scrambler based on proposed random chaotic maps

Cryptography techniques must develop with the developing of wireless communication technologies. One of recent research is chaos based cryptography. Since there is data redundant in chaos signal, and not all chaos maps are random, also the attacker can take a periodic shape of chaos signal and found the system parameters. This paper proposed modifies two of chaos maps (Lorenz, Chen) and using it as pseudorandom number generator (PRNG). By using a test for noisy chaotic dynamics the results showed that the proposed maps are more random compared with original maps. The methods of speech scrambling are proposed in this paper. One of a method is using proposed random Lorenz map (RLM) as PRNG to scramble the values of Wavelet Transform (WT) speech signal. And the other is using proposed random Chen map (RCM) as PRNG to scramble the values of Discrete Cosine Transform (DCT) speech signal. A performance of the scheme is measured. The findings are good. A simulation of the proposed scheme has been implemented by using MATLAB (R2013a) programming language.