Abstract
Since May 2005, numerous laws have been enacted in Japan to protect personal information. The responsibility for protecting personal information has become a critical issue for enterprise-level businesses. Computers and networks are not the only source of sensitive information leaks. In many incidents of information leakage, printed documents are involved. It is now possible to protect confidential and private information by applying the following countermeasures during the printing of documents:
·Copy control by applying a watermark to restrict copying and forgery
·Watermarks for traceability and falsification detection, including background texture watermarks and font embedded watermarks
·Encryption by paper encryption technology
This paper presents an overview of some digital watermarks and paper encryption technology in order to prevent information leaks from paper documents.
