Random Key Permutation Stream Algorithm Based on Modified Functions in AES Algorithm

摘要

The present research deals with the implementation of stream cipher algorithm based on modified AES block cipher concept to achieve high complexity in encryption and decryption processes. Two functions have been modified in the original AES (Modified SubByte and Modified MixColumn) to increase the complexity and keeping the same executed time for both original and modified AES algorithms. The proposed algorithm implemented in stream cipher uses three functions, two of them are Modified SubByte and Modified MixColumn transformation of AES algorithm plus the Block Permutation. Tiny blocks of sizes (2*2, 4*4, 6*6 etc.) have been implemented on the proposed algorithm. The study concluded that the proposed algorithm applied on stream cipher gives successful results with a considerable time for encryption and decryption process.