Multiuser wireless speech encryption using synchronized chaotic systems

This paper proposes a new and efficient chaos-based cryptosystem for multiuser speech encryption. In this regards, Chua chaotic systems are added to the transmitters and receiver to generate the chaotic encryption/decryption keys. The User, who has been selected to send the speech information, encrypts voice information by the chaotic keys and sends it to the base station. To encrypt the speech signal, combination of Chaotic Matrix Operation for Randomization or Encryption and XOR operation is suggested. To analyse the robustness and demonstrate the efficiency of the proposed method, several security analysis is carried out. The key space analysis, key sensitivity analysis and statistical analysis are performed. The simulation results demonstrate that the suggested cryptosystem has much sensitivity to the secret keys, the key space is large enough to resist the brute-force attack and the distribution of the encrypted speech signal has a random-like behaviour. Statistical security analyses for the proposed cryptosystem, from a strict cryptographic viewpoint, shows that the proposed speech cryptosystem is highly secure and has a very powerful diffusion and confusion mechanisms widely used in conventional cryptography. Moreover, in the proposed method sending the voice information by users is done selectively, thus, the proposed scheme, besides that provides the security, also increases the battery life-time of the transmitter.