Integrated Encryption-Steganography for Encryption and Decryption of Gray Level Digital Image

Abstract

     We report in this paper an encryption technique based on pixel value substitution for digital gray level image using chaotic logistic map. The technique takes pixel values as input, uses the map for iteration and a few mathematical operations providing integer values to substitute the corresponding pixels. Chaotic logistic maps are known to have highly complex behavior and are very sensitive to initial condition. It is observed that the map, starting from an initial value and iterating for a number of times, may not provide the substitution value once. As the substituted pixel value is the result of iterating the map by the number of times equal to the pixel value to be substituted, a record is to be kept which shows the number of times the substituted value has occurred during the given number of iterations. For two cycles of substitution, four dummy images or one double size dummy image is constructed from such records using chaos, to be sent to the receiver for decryption. We show that LSB steganography on a support image helps to reduce the number of dummy images. The technique is observed to be very robust and unique.