| 摘要 |
PROBLEM TO BE SOLVED: To suppress the appearance of unauthorized users by monitoring the frequency of decoding processing error in a user terminal and giving the information of the frequency thereof to a center. SOLUTION: A contents decoding key generating part 14 generates a decoding key while using a purchase number inputted by a user. A contents decoding part 15 decodes contents while using the decoding key generated by the contents decoding key generating part 14. An error monitoring part collates a check code, which is decoded together with the contents, with specified code information 5b stored in a ROM 5 and discriminates whether both the codes are matched or not. When both the codes are not matched, the error monitoring part discriminates that decoding processing is not normally finished, namely, that the user does not input the proper purchase number, and the number of times of error generation in a log file 6a is incremented for one. Then, an error information reporting part gives the information of the frequency of the error registered in the log file 6a to the center. |
