Montgomery modular multiplication based data processing method, modular multiplication operation method and device

The invention discloses a Montgomery modular multiplication based data processing method, a modular multiplication operation method and a device. The data processing method includes that calculating a first value s2 by steps: leftwards shifting a modulus N by n-c bits to obtain N1; calculating a value after R N1 modulus is realized to obtain a calculation result s1, and writing s1 into a first memory; executing primary modulo addition operation on the value s1 in the first memory to obtain a calculation result s21, and taking the calculation result s21 as an original value of a second memory to write into the second memory; calling a Montgomery modular multiplier for executing n-1 modular multiplication on the original value s21 of the second memory, and outputting a result R2mod N of n-1 modular multiplication as the first value s2. By application of the method, calculation quantity can be effectively reduced, calculation efficiency is improved, and Montgomery modular multiplication operation in any lengths can be realized.