A novel image encryption technique with four stage bit-interspersing and a 4D-hyperchaotic system

Abstract

This paper introduces a new technique of color image encryption that includes four stages of bit interspersing and a 4D-hyperchaotic system. At first, the pixel values for different RGB channels of a plane color image were represented by an 8-bit binary number. The bit interspersing operation has been implemented on the bit stream generated by considering a particular block size for each color channel and reshaping it to the original size. The cipher image was then constructed by performing a bit XOR operation on the resultant image and the chaotic sequences generated by a 4D hyperchaotic system. The initial state variables of the said chaotic system have been developed from a 32-character secret key. This operation has been repeated three times, considering different block sizes of the newly generated cipher image after each stage. The main strengths of the proposed algorithm are the bit interspersing and image-dependent chaotic key base pixel substitution by bitwise XOR operation. A set of standard security tests are conducted to test the reliability of the suggested encryption method. Comparing the crypto-parameters to other recent works, we find that the proposed algorithm is better than the other methods.