EAES: Extended advanced encryption standard with extended security

Abstract

Though AES is the highest secure symmetric cipher at present, many attacks are now effective against AES too which is seen from the review of recent attacks of AES. This paper describes an extended AES algorithm with key sizes of 256, 384 and 512 bits with round numbers of 10, 12 and 14 respectively. Data block length is 128 bits, same as AES. But unlike AES each round of encryption and decryption of this proposed algorithm consists of five stages except the last one which consists of four stages. Unlike AES, this algorithm uses two different key expansion algorithms with two different round constants that ensure higher security than AES. Basically, this algorithm takes one cipher key and divides the selected key of two separate sub-keys: FirstKey and SecondKey. Then expand them through two different key expansion schedules. Performance analysis shows that the proposed extended AES algorithm takes almost same amount of time to encrypt and decrypt the same amount of data as AES but with higher security than AES.