Performance Enhancement of Blowfish and CAST-128 Algorithms and Security Analysis of Improved Blowfish Algorithm Using Avalanche Effect

There has been a tremendous enhancement in the field of cryptography, which tries to manipulate the plaintext so that it becomes unreadable, less prone to hacker and crackers, and again obtain the plaintext back by manipulating this unreadable text in some way. In this regard, it has modified two secure algorithms Blowfish and CAST-128 which are secret key block ciphers that enhance performance by modifying their function. It has shown that total time taken for encryption and decryption is reduced for both the algorithms after the modification. It has also made an attempt to show that this improvement will not violate the security when compared to that of existing Blowfish algorithm.