| 摘要 |
<P>PROBLEM TO BE SOLVED: To surely discriminate eavesdropping of printing data by an eavesdropper, interposed between a user device and a printer. <P>SOLUTION: A PC1 encrypts the printing data, using an encryption key acquired from the printer 2 at a transmission destination, transmits the printing data to the printer, decrypts the encrypted printing data using a decryption key, corresponding to the encryption key and outputs the printing data with the printer, in the PC, information about the encryption key is embedded in the printing data as electronic watermark, the printing data with electronic watermark to be obtained by the embedding of the information is encrypted and transmitted to the printer, in the printer, encryption key is extracted from the decrypted printing data with electronic watermark, the encryption key obtained by extraction is compared and collated with the encryption key provided to the PC and the presence/absence of eavesdropping of the printing data on a communication path is to be decided. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
