NTT defense method for resisting energy analysis attack

The invention discloses an NTT defense method for resisting an energy analysis attack. According to the NTT defense method, a mask scheme or a messy code scheme is adopted for defending an NTT circuit. In the mask scheme, a serial execution strategy is adopted for two polynomial multiplication operations, two INTT operations are executed serially, a second conversion operation is carried out immediately after a first conversion operation is completed, and two INTT operations are carried out uninterruptedly; in the out-of-order scheme, a pnBF input port used for controlling a butterfly unit to carry out a-b modular subtraction operation or b-a modular subtraction operation is newly added, the modular addition operation sum value of a-path input and b-path input of each level serves as a-path input of the next level, and the modular subtraction operation difference value of the a-path input and b-path input of each level serves as b-path input of the next level. According to the method, the leakage ratio of the