| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an encryption/decryption method capable of encrypting/decrypting on an integer exceeding a range of an effective number for application/software of personal computers without increasing information giving a hint for deciphering by a third party. <P>SOLUTION: An encryption device 1 has a first encryption section 14 that executes a calculation in which a power having an integer X<SB POS="POST">i</SB>smaller than a predetermined number as a base and an integer E as an index is divided by a product N to obtain a remainder and determines the same as an encryption number Y<SB POS="POST">i</SB>of the integer X<SB POS="POST">i</SB>. A second encryption section 15 executes substitution decryption on the encryption number Y<SB POS="POST">i</SB>to obtain an integer Y<SB POS="POST">i</SB>'. The first encryption section 14 converts the integer X<SB POS="POST">i</SB>into an expansion formula including plural integers, and using the expansion formula, a power which has the integer X<SB POS="POST">i</SB>as the base and the integer E as the index is calculated. The second encryption section 15 converts the encryption number Y<SB POS="POST">i</SB>to obtain an expansion formula including plural integers, and using the expansion formula, substitution decryption is made on the encryption number Y<SB POS="POST">i</SB>. <P>COPYRIGHT: (C)2012,JPO&INPIT |
