Performance Enhancement of CAST-128 Algorithm by modifying its function

Abstract

There has been a tremendous enhancement in the field of cryptography, which tries to manipulate the plain text so that it becomes unreadable, less prone to hacker and crackers. In this regard, we have made an attempt to modify CAST-128 algorithm which is a secret-key block cipher so as to enhance performance by modifying its function, which would not only be a secure one, but would also reduce total time taken for encryption and decryption. This paper attempts to improve performance without violating memory requirements, security and simplicity of existing CAST-128 algorithm. The proposed modification is only limited to the change in the implementation of the function F of the CAST-128’s Feistel network. Because the change in the total time taken for encryption and decryption cannot be understood on software implementation, we have implemented VHDL application to show the differences in the delay.