| 摘要 |
PROBLEM TO BE SOLVED: To provide an enciphering method that is a quick enciphering and additionally cannot be decoded by a third person, and to provide an enciphering system using the method. SOLUTION: In this encoding/decoding method, a random number string Ri is generated, on the basis of a given multiple affine key K, and enciphering is conducted with a exclusive-OR between the string Ri and plaintext ABC, etc. Furthermore, the multiple affine key K is automatically and sequentially rewritten to new multiple affine key sequences K', K", and so on, each time the prescribed number of using times is performed, a random number is generated by the sequence of the rewritten multiple affine key, and the enciphering of subsequent plaintext DEF, and so on are continued. Similarly, decoding is also performed by using a multiple affine key, in which self-rewriting is automatically performed each time the fixed number of using times is performed, so that the third person cannot reproduce the multiple affine key and decoding of cryptogram is disabled. |
