METHOD FOR CERTIFYING ELECTRONIC DATA

摘要

PROBLEM TO BE SOLVED: To provide a method for certifying electronic data by which the purchaser of the contents which become the original of an unauthorized copy can be specified with higher evidence. SOLUTION: A provider device 100 sends the contents purchased by a purchaser to the device 200 of the purchaser after enciphering the contents by using the public key of the device 200 of the purchaser. The device 200 produces the electronic signature of the contents by using its own cryptographic key and buries the electronic signature in the sent contents in the form of an electronic watermark. Upon acquiring an unauthorized copy, the device 100 specifies the purchaser who has purchased the contents which become the original of the copy by verifying the electronic signature buried in the contents in the form of an electronic watermark.