With the advent of communication, security has become one of the most important criterions. There lies a behavior between rigid regularity and randomness based on pure chance. It is called a chaotic system, or chaos for short. Chaos is all around us. Chaos has attracted much attention in the field of Cryptography due to its deterministic nature and its sensitivity to initial values. Chaos has remained in darkness for quite sometime owing to its problems in synchronization. This paper has successfully recreated chaotic sequence in the analog domain.
We intend to build a secure digital communication system based on chaotic modulation, cryptography. The proposed system consists of a Chaotic Modulator (CM), a Chaotic Secure Transmitter (CST), a Chaotic Secure Receiver (CSR) and Chaotic Demodulator (CDM) .Chaotic systems require synchronization for practical applications as they are sensitive to parameter changes and initial conditions. The sender and receiver generate the chaotic key using a synchronous system, typically using a Chua’s circuit, where the same set of pseudo random keys is generated simultaneously.
Hardware circuits are capable of producing outputs which closely resemble random behavior. On the other hand, software implementations help in improving the speed of operation and diversity of key. The encryption model uses a software generated synchronization signal for the purpose of ensuring synchronous output between the transmitter and the receiver. This removes the need for a separate channel for synchronization, at the same time improving the security of the model to a great extent as we use the surrounding disturbances around us for encryption.
This encryption model is well suited for a Wide Area Network (WAN) structure owing to its software key diversity. The hard key and soft key, in a way, secure each other. That is, a hacker cannot attempt different hard keys without knowing the soft key, since he will not be able to generate the key stream correctly. In order to attempt to break the soft key, the hacker must necessarily know the hard key and vice versa. To a hacker who probes the data from the public channel, the hardware information is also a secret, proving breaking of the system to be a real challenge.