Voice Security Technology Based On Cellular Automata Research

With the rapid development of network technology and speech coding technology, speech communication technology reaches the breakthrough development and various applications. At the beginning of the communication, identity Authentication can be used to ensure the reliable of the communicants. At the process of speech data transportation, speech encryption can be used to ensure the data security. Because of the speech data's characters of huge data and high demand of real-time, it has a high theoretical and practical value to devote to research the speech security technology.Cellular Automata is a discrete non-linear dynamics system with complicated dynamic properties, simple and high parallel processing architecture which is suitable of VLSI implementation which is very suitable for encryption applications.In this thesis, speech security technology based on Cellular Automata is the important research object. The main results include as follows:(1) Combining with the character of speech transaction, reversible CA is used in the application of speech encryption and construct a speech encryption system based on CA. This system is mainly divided into four parts: preprocess by grouping speech data at the sender port. Encrypt speech data group by group. Decrypt speech data at the receiver port and recover the speech data. This cryptographic system can avoid the problem efficiently of decryption error caused by losing partial cipher in transportation process.(2) The speech encryption algorithm is chosen by introducing a block cipher based on reversible second-order toggle cellular automata and analyzing the problems existing in simulation results. Based on the analysis, a novel cryptographic model based on coupled second-order toggle cellular automata is proposed. Compared with the original algorithm, the novel algorithm can enlarge the key space and make up the problem of the inequality encryption in odd times efficiently.(3) By combining with the simulation data, seeking for regularity of all the elementary cellular automata rule space which is good at speech encryption. Simulation data and analysis on theory shows that, the encrypted speech by this speech encryption system is close to Gaussian noise. Zero error decrypted speech ensures the high quality of speech. At the same time, this method has a good security and flexibility.(4) Bring up a novel hash function based on two-dimensional cellular automata (HTCA). It combines the traditional iterative hash construction method and two-dimensional cellular automata. Analysis on theory and Statistical simulation data shows that, HTCA can successfully resist varieties of cryptanalysis attacks, and it is also flexibility and easy to be implemented with hardware.