Maintaining Secure Level on Symmetric Encryption under Quantum Attack

Quantum computing is currently being researched in many countries, and if implemented in the near future, it may pose a threat to existing encryption standards. In the quantum computer environment, asymmetric encryption can be solved by Shor's Algorithm in polynomial time, and the difficulty of breaking symmetric encryption using brute force is reduced from N times to square root N times by Grover's Algorithm. We take the Advanced Encryption Standard as the theme and increase the key length from the original standard 192 bits and 256 bits to 384 bits and 512 bits, respectively, in order to maintain the security level of AES 192/256 under the environment of quantum computing, so we propose the key schedule of AES 384/512, and write the software in C++ on FPGA. The experimental results show that our scheme can achieve Level III and Level V security levels in a quantum computer attack environment. In addition to increasing the length of the key, we use the LUT method in the process of writing SubBytes to replace the array and speed up the computation to optimize the execution speed. In addition, the proposed scheme is still based on 128-bit computing blocks, rather than computing blocks in larger blocks.