Nonspecific DCT-block fingerprinting based on incomplete cryptography for DRM system

In the present digital world, Digital Rights Management (DRM) is essential to enforce persistent data protection right from the moment it is published. In spite of a need for DRM there are significant weaknesses in the current technology. Generally, DRM system is achieved with individual function modules of cryptography, fingerprinting and so on. In this typical system flow, all digital contents are temporarily disclosed with perfect condition via decryption process. This paper describes the elemental idea of a DRM method which is composed of an incomplete cryptography based on nonspecific DCT-block (Discrete Cosine Transform) and user fingerprinting mechanism to control the quality of digital contents. There are two fundamental steps in our proposed cryptography: incomplete encoding and incomplete decoding. These two steps will create the scrambled content using as trial content and fingerprinted content is used to prevent unauthorized duplication or business of digital contents, respectively. Experimental results on standard JPEG (Joint Photographic Experts Group) format show that the proposed method is suitable for DRM in the network distribution system.