IMPLEMENTATION OF ADVANCED ENCRYPTION STANDARD IN SIMPLE, COMPOSITE AND EXTENDED MODE

Abstract

Cryptography is a technique related to aspects of information security such as data confidentiality, data
integrity and entity authentication. In data and telecommunication systems, Security is the most important part for an
effective communication, where to increase the security as well as complexity, more randomization in secret keys is
necessary to enhance the cryptography algorithms. In AES, Even though the round keys have high security, Power
analysis attack and Saturation attack are effective to the key expansion algorithm of AES due to reducible key rounds
and it leads to security problems. AES in simple, composite and extended mode, the main objective of the AES in
extended field is to reduce the memory required to perform sub bytes by replacing the two 256 byte lookup table
(LUT’s) that is one for encryption and the other for decryption. The cost of this replacement leads to an increase in
combinational logic which is used to perform affine transformation. The field over GF(28) called an extended field
while the more compact representation GF(24)2 is called a composite field. It reduces the size of LUT’s to 8 bytes.
The designs presented in this paper is simulated using Xilinx 14.2 software.