256-Bit AES Encryption Using SubBytes Blocks Optimisation

Abstract

Most applications, like e-commerce, military etc., place a significant emphasis on hardware security. Hash functions, public (asymmetric) key cryptography, and private (symmetric) key cryptography are the three different categories of cryptographic techniques. The same key is used for encryption and decryption in symmetric key algorithms like advanced encryption standard (AES) and data encryption standard. It is a lot quicker, simpler to use, and uses less computing power. A powerful cryptographic technique which can be used to ensure the security of electronic information is termed advanced encryption standard (AES). It appears to be immune to the majority of attacks. In this paper, we suggest a 256-bit AES method that is efficient for area and power in the key scheduling and substitution byte blocks. Instead of 128-bit operation, internal operations are 32-bit operations are performed, which is a new approach of algorithm optimisation. The four operations substitution bytes, shifting rows, mixing column, and adding round key are used to build the AES algorithm. After encryption, the encrypted message will be sent across the channel. The message will be decrypted at the recipient end using the same encryption key. The key size of the 256-bit AES method is 256 bits, yet all of data size is just 128 bits. Data contain the encrypted message, the text of the cypher, and the decrypted message.