others from reading the document (see website of Adobe??? Systems Inc., ???with Adobe Acrobat, PDF can be used more effectively??? (http://www.adobe.co.jp/acrofamily/features/acro_nikkei/page4.html)). [0006] When printing such encrypted document data created by a personal computer (PC) on a printer connected to a network such as a local area network (LAN), an application decrypts the encrypted doc