Advanced Encryption Standard and Fault Detection for High Performance
K. Rahimunnisa · 2013
Advanced Encryption Standard (AES) algorithm is a symmetric block cipher that can encrypt and decrypt the information. This paper presents the AES Algorithm. The look up table is used for implementing the AES S-box and inverse S-box. The AES has been built as the first choice for many cryptographic applications because of the high level of security. However the faults that can accidently occur in the hardware implementation may cause erroneous encrypted or decrypted output that, results in losing the original information. At the end of this design, a parity based fault detection scheme for high performance AES is also presented. Cryptography is the practice and study of hiding information, which plays an important role in the security of data transmission. Apart from its uses in Military and Government to facilitate secret communication, Cryptography is used in protecting many kinds of civilian systems (1). The Encryption algorithm is a set of well defined steps to transform data from a readable format to an encoded format using the key. This algorithm provides Confidentiality, Authentication and integrity. Encryption algorithms are broadly classified as Symmetric or Asymmetric algorithms based on the kind of keys used. For symmetric algorithm the Encryption and Decryption uses same key. A few well-known examples are: DES, AES. Asymmetric algorithm uses separate keys for both Encryption and Decryption. The decryption key is typically kept secretly, therefore called private key, while the encryption key is spread to all who might want to pass the encrypted messages, therefore called public key. Symmetric algorithms have the advantage of not consuming too much computing power. Advanced Encryption Standard is one of the Symmetric Algorithm (2). Advanced Encryption Standard, based on the Rijndael algorithm is such a Symmetric algorithm for Encryption. The Advanced Encryption Algorithm (AES) was published by NIST (National Institute of Standard and Technology) in 2001 (2). NIST selected Rijndael as the proposed AES algorithm. Rijndael has many advantages. It has resistance against all known attacks. The design is simple. It has high speed and the code is compact. AES is a symmetric block cipher that replaced DES. AES has a wide range of-application. The AES has a block length of 128 bits and key length of 128,192 or 256 bits. The basic unit of processing in the AES algorithm is a byte. The AES operates on a 4x4 array of bytes which is called a state. The state undergoes 4 transformations which are namely the AddRoundKey, SubByte, ShiftRow and MixColumns transformations. Among these transformations in the AES, the S-Box and inverse S-Box are alone nonlinear and these occupy much of the total AES area. Fault detection scheme in the AES implementation is important in order to make the standard robust to internal faults. There exist many fault detection schemes for the AES implementations. For the fault detection in the AES, redundant units may be used (4-5). The fault detection