Modification of Vigenere Algorithm and One Time Pad Using Rivest Code 6 (RC6) Key Expansion

Abstract

Information technology that is increasingly developing today must be balanced with information security. Good security can minimize the possibility of information being stolen by cryptanalysis, one way is by applying cryptographic techniques. Vigenere Cipher is a key symmetry algorithm that uses a substitution technique that uses two letters encoding the original message. Vigenere cipher and one time pad have disadvantages because they use short keywords and their use will be repeated. The key expansion used is part of the RC6 encryption algorithm combined with Vigenere and One time pad to cover the weaknesses of the algorithm. The purpose of this study is to produce new variations with the modification of the vigenere cipher algorithm and one time pad by adding a key expansion process and tested using the avalance effect. Test results conducted based on modifications can achieve a high level of avalance effect which is 51.76%