| 摘要 |
PROBLEM TO BE SOLVED: To provide a method, a device, and program for ciphered information generation which generates ciphered information at a high speed by shortening the time needed to generate an prime number and a recording medium where the program is recorded. SOLUTION: This ciphered information generating device which generates the ciphered information by ciphering information by using the prime number is equipped with a ciphered information generation part 3 which generates the ciphered information C with inputted bit width L, a Montgomery arithmetic part 5 which performs Montgomery arithmetic for a number as a prime number candidate, and a control part 1 which makes the Montgomery arithmetic part 5 carry out Montgomery arithmetic based upon last generated ciphered information C as an initial value when the number of digits of the ciphered information generated by the ciphered information generation part 3 exceeds (L/4) bits and makes the ciphered information generation part 3 update the ciphered information by using the number decided as a prime number through the Montgomery arithmetic as a new prime number.
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