International Association
for Cryptologic Research

We propose some quantum circuit implementations of AES with the following improvements. Firstly, we propose some quantum circuits of the AES S-box and S-box$^{-1}$,which require fewer qubits than prior work. Secondly, we reduce the number of qubits in the zig-zag method by introducing the S-box$^{-1}$ operation in our quantum circuits of AES. Thirdly, we present a method to reduce the number of qubits in the key schedule of AES. While the previous quantum circuits of AES-128, AES-192, and AES-256 need at least 864, 896, and 1232 qubits respectively,our quantum circuit implementations of AES-128, AES-192, and AES-256 only require 512, 640, and 768 qubits respectively, where the number of qubits is reduced by more than 30\%.