Comparative Study of CAST and TWOFISH algorithm using various Modes of Operations

Abstract

Encryption is a process to encode a message, file, image or video data (intelligent data) to convert it into a cipher data (i.e. non-intelligent data). This study is about to encrypt data (text and image file) to analyze the cipher text which was produced by the given algorithms (CAST and Twofish) in the scenario of memory consumption and time taken to encrypt it and vise-versa. Here file encryption is used to encrypt the data file while storing data in local drive for the security purposes which is achieved by converting data into cipher data by implementing different versions of CAST and Twofish encryption algorithm, which is then analyzed through their performance (time and memory) analysis. CAST encryption and Twofish encryption algorithm are used with block cipher modes of operations to implement and analyze. ECB (Electronic Code Book), CBC (Cipher Block Chaining), CFB (Cipher Feedback Mode), OFB (Output Feedback Mode and CTR (Counter Mode) are the modes of operations used in this study. Text and image files of different sizes are input for this study and different performance parameters like PSNR, NPCR, UACI, Histogram, and encryption / decryption time are used to measure the strength of the algorithms. Based on the analysis done during this study, it is found that for the image and text data, CAST-128 algorithm is found to be approximately three times better in comparison with other algorithm on encryption and decryption time analysis. Similarly Twofish algorithm is found to be better for the case of throughput analysis for both text and image data. In terms of memory utilization, Twofish-128 is found to be consuming less memory compared to other algorithms. Similarly, visual assessment and differential analysis for image data analysis, all the algorithm seems to be performing best since no difference in original and retrieved image data. And for the case of statistical analysis, there seems to be no difference in original and retrieved image histogram. Keywords: encryption, CAST, Twofish, block modes of operation.