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Increasing the security of block ciphers is a topic of great interest today, and thus there is a variety of work to enhance the strength of such ciphers. There are also many studies focusing on the Advanced Encryption Standard (AES), presenting methods of making block ciphers dynamic to improve their security. Animating methods can perform block cipher transformations such as substitution or permutation, or both. In this article, we propose an algorithm to create new, key-dependent XOR tables from an initial secret key. At the same time, we prove that in the ciphertext the new XOR operation can preserve the independent, co-probability distribution of the random key. We then apply these new XOR tables to make AES dynamic at the Addroundkey transformation. We created a considerable number of XOR tables, about ${(16!)}^{2}$ tables. With such a vast number of key-dependent dynamic XOR tables, cryptanalysts will have great difficulty finding the actual XOR table used in the modified AES block cipher. Therefore, with our new XOR tables, AES will be significantly enhanced. |
