Modified Blowfish Algorithm Based on Improved Lorenz Attractor

Abstract

Image security becomes important topic because of increasing image usage in communication besides assures information security which is unseen in these images such as military and medical images. Blowfish is a superb symmetric cryptography that ensures a high degree of resistance to attacks. The proposed system modifies Blowfish algorithm by substituting the function in blowfish round with light weight function to save memory and resources of the platforms and Using 3-D chaotic system (Improved Lorenz) that work as a key timetable for creating Blowfish sub keys in order to increasing randomness of the encrypted image. Because no hardware multiplier is required, this technology may be employed in high-speed applications. Both 3-D chaotic circuit and modified blowfish encryption/decryption schemes are designed using VHDL and simulated by Xilinx ISE 14.7. The proposed system has been embedded in an FPGA device XC5VLX50T to examine modification of Blowfish encryption algorithm efficiency, the system is examined by MATLAB and passes NIST statistical suite test. This system only used 6 % of the FPGA Virtex 5 kit’s slices, with an operating frequency of 351MHz.