Secure Communication Scheme for Color Image Based on Index Technology

Abstract—A secure communication scheme for true color image was proposed. It is aimed at the hiding problem of a huge amount of true-color image data in the covert communication and maintaining the good visual quality of carrier image. Secure communication is achieved by combining encryption and hiding. Encryption on secret image is performed in the spatial domain of carrier image. Instead of changing pixel physics position or gray value, encryption method is searching the index value of secret image and hiding it in carrier image. Carrier image is designed as a palette, and the use of chaotic signal to act on the carrier image makes palette colors rich and evenly distributed. Each pixel of secret image is adaptively mapped to a subscript in palette by the minimum principle of Euclidean distance. Secret image is compressed and encoded as a data stream during encryption, reducing the amount of data to be hidden. Secret image is hidden in the wavelet domain of carrier image by using the lifting wavelet transform and multi-channel spread-spectrum embedded way. Simulation experiments show that this secure communication scheme reduces hidden data amount and improves information hiding transparency to ensure the concealment and safety of communication. Keywords-Secure communication; Image compression; Chaotic system; Index technology I