A Comparative Study of AES Encryption Decryption

AES (Advanced Encryption Standard) is an effective encryption algorithm in applications like internet to provide cyber security and also in smart cards. In November 2001, the National Institute of Standard and Technology (NIST) of the United States choose the Rijndael algorithm as the suitable Advanced Encryption Standard (AES) to replace the Data Encryption Standard (DES) algorithm. AES is used in almost all network based applications to ensure security. The core computation of AES, which is performed on data blocks of 128 bits, is iterated for several rounds, depending on the key size. The strength of AES is proportional to the number of rounds applied. The number of rounds is fixed to 10, 12 and 14 for a key size of 128,192 and 256 bits respectively. The AES functional calculations include four transformation stages, which are Sub Bytes, Shift Rows, MixColoumns and AddRoundKey. In this paper, we have critically analyzed various AES techniques and also have covered AES overview such that it’s Structure, Transformation Functions and Key Expansion.