Enhancing Security of Vignere Cipher using Modified RC4

Encryption is a way to enhance the security of a message or file by scrambling the contents so that it can be read only by someone who has the right encryption key to unscramble it. Encryption does not of itself prevent interception, but denies the message content to the interceptor. RC4 is one of the most popular encryption algorithms and finds its applications in many security protocols such as Wi-Fi Protocol Access (WPA) and Wired Equivalence Privacy (WEP). Although being a versatile encryption technique, RC4 faces numerous loopholes and weaknesses. Encrypted messages can sometimes be broken by cryptanalysis, also called codebreaking. It uses three secret keystwo secret keys K1 and K2 as seeds for Enhanced RC4 and K3 as the key for Vigenere Cipher substitution. It also uses two SBoxes S1 and S2. Both of them contain N elements from 0 to N-1. Although being a versatile encryption algorithm, Vigenere Cipher is not resistant to the Kasiski Attack. Through Cryptanalysis, one can determine the frequency of each letter and find a pattern in the Cipher text as well as the length of the key. In this paper, we propose an enhancement to the RC4 algorithm by converting it into a product cipher. Then we attempt encryption combining the 2 encryption techniques, Modified RC4 and Vigenere in a systematic manner. General Terms Cipher, Security, Stream Ciphers, Product Ciphers