An Adaptive Control Approach to Securely Transmit Colored Images using Chaos-based Cryptography

This paper introduces a new technique for transmitting colored images, using chaos-based secure communication. The colored image is converted into three parallel time series that correspond to the basic RGB color components. The time series are used to modulate the parameters of the chaotic transmitter, using a simple digital encryption function. At the receiver side, a decryption function is used to reconstruct the original time series to reassemble the transmitted colored image. Synchronization between the transmitter and the receiver is achieved, using an adaptive control approach that relies on Lyapunov-based techniques. A single time series of the chaotic transmitter is transmitted in the public communication channel to promote security and utilization efficiency of the available transmission bandwidth. To implement the suggested technique, a Duffing oscillator is used, which has three parameters that are alternating between two levels, corresponding to the changes in the binary levels of the bit stream of the converted color image. Eight different chaotic attractors are generated resulting in a much superior performance, compared to the classical modulation-based chaotic communicators. Arriving at the best parameter update law that guarantees both stability and satisfactory transient performance is carefully investigated to highlight the advantages and limitations of the proposed strategy. Finally, a discussion is submitted, with comments regarding the design/tuning effort, real-time compatibility, and possible extensions to the proposed system.