A switch-modulated method for chaos digital secure communication based on user-defined protocol

In this paper, a scheme for digital secure communication is proposed. In this scheme, we use a control function which is defined by two communicants based on chaos synchronization. At first, different signals are sent according to the promissory transmission situation of control signal, then transmission field which is consist of protocol and transmission content is produced. After these processing, the correlation of the transmitted signals are decreased. In addition, the using of the compound non-linear function transformation can further intercalate the secret key, so a determined intruder is very difficult to retrieve the message using forecasting method.