METHOD AND SYSTEM FOR DETECTION OF ADDITIONAL INFORMATION

摘要

PROBLEM TO BE SOLVED: To provide a method and a system capable of safely detecting the additional information electronically embedded, at many and unspecified places. SOLUTION: A server reads the data where the additional information is embedded and then asks an anti-tamper device including a secret key to judge the embedding of the additional information. At the same time, the server reads a mask pattern out of the mask data, calculates the inner product of the mask pattern and the data including the embedded additional information and sends this inner product to the anti-tamper device. The anti-tamper device adds the inner product value sent from the server at the time of judging the embedding of the additional information and judges the threshold using the secret key. When the threshold is judged, a detecting mask pattern is produced from the secret key included in the anti-tamper device and the embedding of the additional information is judged based on the inner product value of the detecting mask pattern and the data received form the server.