Active watermarks and watermark agents

US6754822B1 · kind B1 · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventor

• Jian Zhao · Dongguan, CN

Key dates

• Filing date: Apr 30, 1998
• Grant date: Jun 22, 2004
• Expiry date: Apr 30, 2018

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F2221/2143
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

Techniques for protecting the security of digital representations, and of analog forms made from them are presented. The techniques include authentication techniques that can authenticate both a digital representation and an analog form produced from the digital representation, an active watermark that contains program code that may be executed when the watermark is read, and a watermark agent that reads watermarks and sends messages with information concerning the digital representations that contain the watermarks. The authentication techniques use semantic information to produce authentication information. Both the semantic information and the authentication information survive when an analog form is produced from the digital representation. In one embodiment, the semantic information is alphanumeric characters and the authentication information is either contained in a watermark embedded in the digital representation or expressed as a bar code. With the active watermark, the watermark includes program code. When a watermark reader reads the watermark, it may cause the program code to be executed. One application of active watermarks is making documents that send messages when t…