Study On Memeristor Chaos And Its Application In Speech Secure Communication System

Chaotic signal has lots of performances such as high sensitive to initial value, noise–likecharacteristics and continuous broadband power spectrum. There is a natural relationship betweenchaotic dynamics and traditional cryptography, in which chaos have some main characteristicscorresponded to cryptography. Chaotic singnals can be used in the domins of securecommunications, cryptosystem and computer, etc., as pseudo random sequences.Memristor (memory resistor) is another new nonlinear basic circuit element in addition tothree basic ciecuit elements of resistor, capacitor and inductor, which has the characteristic ofmemory. Since a real TiO2 memristor was first found at HP laboratory and reported, the researchfor memristor theory and applications has been started. We can construct the chaotic system basedon memristor, and the research results show that memeristor-based chaotic system has somespecial characteristics of more sensitive to initial conditions, in which general chaoticsystems hasnot. Based on the research for memristor and metistor chaos, we design a scheme of speechsecurity communication using the pseudo random sequencese geneared by memristor chaos,implementing two-ways speech security communication for point-to-point in local area network.(1) The basic theory of chaos is studied. We replace the Chua’s diode with a flux-controlledactive memristor and obtain a complex new 5-D menristor-based chaos circuit, based on thehyperchaotic Chua’s circuit. The dynamical behaviors of the proposed chaotic system areanalyzed, including symmetry, equilibria and stability of the system. And the differentcharacteristics between the traditional chaotic systems and memristor-based chaotic system areanalyzed.(2) Based on the new memristor chaotic equation, the system was discreted to get PNsequences, at the same time, the sequence performance was measured by test software which waspublished by NIST, and the test results showed that the performance was good enough to be usedto the secure communication system.(3) The basic theory of cryptography is studied. The realationship between cryptographyand chaotic has been analyzed and compared from different angles. Some methods of chaoticencryption algorithm are deeply studied. For the chaotic sequence has an infinite key space andthe stream algorithm is simple, the encryption performance is perfect and fast. Chaos streamcipher encryption method is feasible in the real-time voice communication.(4) A formule of voice encryption system based on memerister is proposed, thepoint-to-point and two-ways speech security communication system has realized, we make the memeristor chaotic sequence as encryption sequence, use the chaos stream cipher encryptionmethod to encrypt the speech data. Due to the high-dimensional chaotic systems has a large keyspace and the complex topology of memristor-based chaotic system, the security of this voiceprivacy system is high.