なぜFHEで巡回シフトが出来るのか theory Bootstrapping for Approximate Homomorphic Encryption > Rotation 参考文献 discrete signals - What happens to frequency domain components if I circular-shift the time domain samples? - Signal Processing Stack Exchange Shift Theorem | Mathematics of the DFT Ring Structures and the Discrete Fourier Transform Polynomial multiplication over finite fields in time O(n log n)