Design And Implementation Of Chaotic Voice Encryption System Based On DSP

With the advent of information age, protection of information security issues is very important. Voice information is the basis mode of daily intercommunion, and voice secrecy communication is one of communication to prevent confidential information being stolen. Data encryption technology is the primary means of voice secure communication. Because chaos has a natural link with cryptography, chaotic sequence has good application prospects in the field of encryption. DSP (digital signal processor) is specially designed for processing digital signal, and it can quickly and efficiently implement complex algorithms. Against this background, this article realizes digital chaotic sequence in the use of DSP and applies the NIST testing standards to examine the quality of sequence. Finally, a chaotic voice encryption system is implemented.The main work of this thesis is:(1) Based on the noted Sprott system, the new chaotic systems can be constructed with more complex dynamics by introducing the non-linear items. The detailed dynamical behaviors of the new system are further investigated, including equlibria and stability, various attractors, bifurcation analysis and Lyapunov exponents'spectrum. Besides, the analog circuits of the new systems are also designed.(2) To implement the chaotic PN sequences in digital form, The TMS320VC5502 made from TI is a good choice. First of all, we discretize and quantize the news system to implement the continuous system in a digital form and obtain a binary digital sequence. Then, the UART of TMS320VC5502 chip can output the chaotic PN sequences. To making sure that the discrete system is still chaos, we observe the analog attractors which are converted from digital sequences by D/A chip TLC7528.(3) In order to apply the chaotic sequence to the digital chaos encryption system, we shoule analyse the quality of sequence. The STS package launched by NIST (National Institute of Standards and Technology)is currently the most authoritative tool which is used to test the performance of pseudo-random sequence. This thesis not only test the chaotic sequence based on Sprott system, also M series,Lorenz and Chen systems,R?sslor hyper-chaotic system sequence are analyzed. The comparisons find that Sprott digital chaotic sequence has good performance and can be used in encryption system.(4) A formule of voice encryption system based on DSP is proposed, including hardware platform,software process and system function modules. Applied the digital chaotic sequence generated by DSP, voice encryption and decryption are realized with XOR algorithm. In addition, taking into the account of channel bandwidth issues, this system use the G.726 standard. The good randomness of the Sprott chaotic sequence makes the high security of the xoice privacy system.