| 摘要 |
PROBLEM TO BE SOLVED: To provide a safety-provable and highly efficient method for ciphering public key that is used in a cipher communication method in which the transmitter creates a cryptogram in a transmitter device 100 using the public key of a receiver and transmits it to the receiver device 200 via a communication line 300, and in which the receiver deciphers the cryptograph using a secret key. SOLUTION: A plain text space is set so as to be an open interval (0, 2k-2) and a subset of small surplus groups with respect to n=pdq (p, q: prime numbers, and pq is k-bits), and an algorithm is composed so as to clarify the relations among quadratic equations existing plurally. Thus, this system enables proof of safety by the equivalence to the difficulty of factorization problem, and also enables deciphering processing speedier than with a conventional system.
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