A Novel Design of Blowfish Algorithm for Image Security

Abstract

In order to improve the security and efficiency of image encryption systems comprehensively an image encryption based on enhanced design of Blowfish scheme is proposed. The proposed system is employed block based image encryption technique combined with chaotic map properties. Firstly the digital image is scrambled and decomposed into several key based blocks randomly to decorrelated the relationship between original and processed image then each block is passed through an enhanced blowfish algorithm. The enhancement in design is to gain advantage of the strong facility, which is maintained by blowfish algorithm by overcoming its flaws, which leads to a significant improvement in security/performance. As a result the proposed system offers good performance for image encryption. The proposed algorithm is 320-bit Blowfish-like block cipher, where cascaded looking composition of F-functions is used instead of rounds. The key is accepted a variable length up to 400 bytes. The pragmatic aim of the proposed system is to decrease memory requirements and execution time while keeping the cipher simple and highly adaptable to future demands. To ensure improved encryption algorithm, the implementation of both techniques has been carried out for experimental purposes which is showed that the original image has a flat histogram after encrypted, a decreasing correlation between adjacent pixels in all color components and increasing entropy for the cases studied. The proposed algorithm has a sufficiently large key space and a very high sensitivity to the key. A comparative study with previous Blowfish algorithm shows the superiority of the modified algorithm.