2012 IEEE International Conference on Advanced Communication Control and Computing Technologies (ICACCCT) ISBN No. 978-1-4673-2047-4 Organized by Syed Ammal Engineering College, Ramanathapuram, Tamilnadu 197 Study of Avalanche Effect in AES Using Binary Codes Chandra Prakash Dewangan 1 , Shashikant Agrawal 2 Akash Kumar Mandal 3 , Mrs. Archana Tiwari 4 Department of Electronics and Telecommunication Chhatrapati Shivaji Institute of Technology Durg 1 2 , India, Department of Electronics and Instrumentation Chhatrapati Shivaji Institute of Technology Durg 3 4 , India, 1 cpdewangan04@gmail.com 2 shashikantagrawal @csitdurg.in 3 akashmandal@csitdurg.in 4 archanatiwari@csitdurg.in Abstract — With the fast progression of digital data exchange in electronic way, security of information is becoming more important in data storage and transmission. Cryptography has come up as a solution which plays a vital role in information security system against malicious attacks. This security system uses some algorithms to scramble data into scribbled text which can be only being decoded or decrypted by party those possesses the associated key. These algorithms consume a significant amount of computing resources such as CPU time, memory and computation time. In this paper a most widely used symmetric encryption techniques i.e. advanced encryption standard (AES) have been implemented using MATLAB software. After the implementing this encryption technique, analysis is done by using a parameter called Avalanche effect. Plaintext and encryption key are mapped in binary code before encryption process. Avalanche Effect is calculated by changing one bit in plaintext keeping the key constant and by changing one bit in encryption key keeping the key constant, Experimental results shows that the proposed algorithm exhibit significant high Avalanche Effect which improves the level of the security. Keywords — Advanced Encryption Standard (AES), Avalanche Effect, Ciphertext, Secret key. I. INTRODUCTION Transmission of sensitive digital data over the communication channel has emphasized the need for fast and secure digital communication network to achieve the requirement for integrity, secrecy and non reproduction of transmitted information. The main goal of cryptography is to keep the data secure from unauthorized access. Cryptography provides a scheme for securing and authenticating the transmission of information across insecure communication channels. It enables us to store susceptible information or transmit it over insecure communication networks so that unauthorized persons cannot read it. [1] A Cryptographic method of scrambles the content of digital data like text, image, audio and video to make it unreadable or unintelligible for others during transmission. [2] A system that performs encryption decryption is called cryptosystem. The complexity of encryption process depends on algorithm used for encryption, software used and the key used in algorithm to encrypt or decrypt the data [3]. There are chiefly two types of cryptographic algorithms: symmetric and asymmetric algorithms. Symmetric systems e.g. Data Encryption Standard (DES), 3DES, and Advanced Encryption Standard Fig 1 Overview of the field of cryptography (AES) uses same key for the sender and receiver both to encrypt the information and decrypt the cipher text. Asymmetric systems e.g. Rivest-Shamir-Adelman (RSA) & Elliptic Curve Cryptosystem (ECC) uses different keys for encryption and decryption. Symmetric cryptosystems is more appropriate to encrypt large amount of data with high speed. After far-reaching survey of various research papers it is observed that an encryption algorithm should produce significant change in the encrypted message when a small change is made in original message. In research papers [8] and [9] authors analyzed various cryptographic algorithms using a parameter called Avalanche Effect. In this paper we proposed an enhancement in AES algorithm using binary codes. This proposed algorithm is expected to provide significant high Avalanche Effect. II. CRYPTOGRAPHY Depending upon the number of keys used, cryptographic algorithms can be classified as asymmetric algorithms (public key) and symmetric algorithms (secret key). In Symmetric keys encryption or secret key encryption identical key is used by sender and receiver. Data Encryption Standard (DES), 3DES, and Advanced Encryption Standard (AES) are the example of Symmetric key encryption algorithms. In Asymmetric keys encryption two different keys (public and private keys) are used for encryption and decryption. Public key is used for encryption and private key is used for decryption Rivest-Shamir-Adelman (RSA) and Elliptic Curve Cryptosystem (ECC) are the example of asymmetric key algorithms. [4] A symmetric cryptosystem has five ingredients: A. Plain text This is the original data or message to be transmitted that fed into the algorithm as input.