Improved Dynamic S-Box generation using Hash function for AES and its Performance Analysis

With the development of information technology and increasing demands for information security, various encryption methods have been attracted more and more attention in recent years. AES is one such symmetric key algorithm used for securing the data that transmits in the Internet. The strength of AES block cipher depends on the S-Box structure which is a nonlinear substitution operation. S-Boxes are fundamental component of symmetric key algorithms which performs substitution. Since the Substitution boxes are dynamically created, this fact makes it clear that both linear and differential cryptanalysis cannot be done on Dynamic S-Boxes. They are basically used in block ciphers to make the affiliation between key and cipher text more unfamiliar. There are lots of techniques used for generation of S-Box such as key dependent S-Box in which S-Box depends on the key, Bijection, Strict Avalanche criterion etc. This paper briefly analyzes the structure of AES algorithm and a dynamic S-Box is generated based on hash function. Also, the eminence of generated S-Box is been experimentally evaluated and compared along with the original AES for the simulation time.

1. INTRODUCTION

In day today’s digital world the arena of fast and secure communications with peer network is playing a imperative role to conduct digital transaction more secure in contrary to various types of known and unknown attacks and the study of providing such a protected communication which is liable for this is termed as Cryptology. The primogenital methods to armor information are privacy are cryptology, steganography and watermarking. The key objective behind all of these approaches is to secure the data. With this objective the study of cryptology can be further alienated into two main areas; cryptography and cryptanalysis. Cryptography is the study of designing and developing encryption algorithms that meets certain design criteria and Cryptanalysis is the field of devising new methods to decipher the encrypted data. Cryptography can be categorized into two main categories, one is symmetric encryption algorithms which uses a single private key and the other is asymmetric encryption algorithm which uses two separate keys. Symmetric encryption algorithms can be implemented in two ways namely Block ciphers and Stream ciphers depending upon how the input data block is processed. Certain instances of block ciphers are implemented as Advanced Encryption Standard (AES), Data Encryption Standard (DES), International Data Encryption Algorithm (IDEA) etc.