A Novel Approach for Speech Encryption: Zaslavsky Map as Pseudo Random Number Generator

摘要

Recently emerged interest in the transfer of information, whether speech or image or text information. To maintain the confidentiality of such information we need to encrypt it. This paper proposes a new cryptography technique for speech to increases the security of the data meant to be transferred on an insecure medium. The proposed scheme for speech encryption is based on Zaslavsky map and Cat map transform. In this work, the original speech signal is first compressed by discrete cosine transform (DCT) to reduce the residual intelligibility and then the plain data is hidden using random numbers generated using Zaslavsky map. The output data is then processed by Cat map to perplex the data samples so as to make the information unable to understand by an intruder. These two lower dimensional chaotic maps act together to make encryption in higher dimensional space which expands the key space and consequently enhances the security against brute force attack. The resulting system gives more complex dynamical properties proofed with good randomness and unpredictability. Various analyses such as signal to noise ratio (SNR), key space, correlation and brute force attack have been carried out. The analysis shows that the proposed algorithm is computationally simple and efficient compared to conventional higher dimensional chaotic maps. The signal obtained in the proposed technique after decryption at the recipient end is a replica of the original signal which was meant for encryption.