ENCODER, DECODER, DATA PROCESSOR, NETWORK SYSTEM, DATA PROCESSING METHOD, RECORDING MEDIUM AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a network system which can prevent data to be protected surely from being led out, by an outsider or a user who are not allowed. SOLUTION: A file server 130 stores results (encoded data d2) in a data base 140, where the data d0 to be protected are encoded by using first data d1 and second dataαwhich have specified rules. A monitor server 120 monitors data on a communication line 160, and can obtain the first data d1 from data X by using the second dataαwhen the data X are decoded. When the specified rules which the first data d1 has are detected from analyzed results of the first data d1, the monitor server 120 recognizes that the data X are the encoded data d2, and performs processing such as communication cutoff.