Chaos Image Encryption Using Transposition and Pixel Shuffling

The advent of wireless communications, both inside and outside the home-office environment has led to an increased demand for effective encryption systems. The beauty of encryption technology comes out in more pronounced way when there is no absolute relation between cipher and original data and it is possible to rebuild the original image in much easier way. As chaotic systems are known to be more random and non-predictable, they can be made utilized in achieving the encryption. The transposition technology of encryption systems requires scrambleness behaviour in order to achieve the encryption of the data. This scrambleness behaviour can be derived from the randomness property of chaos which can be better utilized in the techniques like transposition system. In wireless communication systems, bandwidth utilization is an important criterion. In order to use encryption system in wireless communication; key space plays an important role for the efficient utilization of the bandwidth. In this paper we present a chaos based encryption algorithm for images. This algorithm is based on pixel scrambling where in the randomness of the chaos is made utilized to scramble the position of the data. The position of the data is scrambled in the order of randomness of the elements obtained from the chaotic map and again rearranged back to their original position in decryption process. The same algorithm is tested with two different maps and performance analysis is done to select best suited map for encryption. Keywords - chaos, Encryption systems, Transposition technique I. INTRODUCTION The amazing developments in the field of network communications during the past years have created a great requirement for secure image transmission over the internet. Internet is a public network and is not so secure for the transmission of confidential data. The advent of wireless communications, both inside and outside the home - office environment has lead to an increased demand for effective encryption systems. The beauty of encryption technology comes out in a more pronounced way when there is no absolute relation between cipher and original data and it is possible to rebuild the original image in much easier way. In wireless communication systems, bandwidth utilization is an important criterion. In order to use encryption system in wireless communication key space plays an important role for the efficient utilization of the bandwidth. II. PROPOSED ALGORITHM The image used will have its RGB colours extracted and its RGB values transposed to obtain an image which will then be encrypted to obtain ciphered image. The ciphering of the image for this research will be done using the RGB pixel values of the image only. In this method, there will be no changes of the bit values of the image used and no pixel expansion at the end of encryption and decryption process. The numerical values of the pixels are displaced from their respective positions and the RGB values are interchanged in order to obtain the ciphered image. This implies that, the total change in the sum of all values in the image is zero. Therefore, there is no change in the total size of the image during encryption and decryption process. The images are looked at as a decomposed version in which the three principle components which form the image were chosen to act upon by the algorithm. The R-G-B components were considered as the triplet that forms the characteristics of a pixel. The pixel is the smallest element of an image that can be isolated and still contains the characteristic found in the image. The RGB values are shifted out of their native pixel positions and interchanged within the image boundaries. The Shift displacement of the R, G and B Values known as the component displacement factor array was different for