COMMUNICATION SYSTEM, METHOD THEREOF, TERMINAL USED FOR THE SAME AND PROGRAM-RECORDED MEDIUM

摘要

PROBLEM TO BE SOLVED: To enable only a specified receiver for receiving specific information as well as main information. SOLUTION: A telegram 7 for conveying only to a specified receiver by a transmission terminal is prepared, this telegram 7 is embedded into an electronic watermark wallpaper (background information) as an electronic watermark, this embedded wallpaper 5 is attached to a general receiver destination information 8, together with a transmission identification ID (a key for electronic watermark insertion), a transmission telegram is prepared and then transmitted. On a reception side terminal, it is determined from the wallpaper 5 whether or not there is watermark information and if there is, a password is inputted and when the correct one is inputted, extraction of watermark information is performed.