Fingerprinting method using invariant offset huffman code length feature

This paper describes an experimental system integration of Digital Rights Management (DRM) architecture and fingerprinting which is composed of an incomplete cryptography scheme using invariant offset huffman code length feature and the user identification mechanism to control the quality of the digital contents. We adopt the AC-coefficent huffman code length feature of the DCT coefficient in the JPEG codec to the implement incomplete cryptography. In the our scheme, the copyright information is embedded into the decoded content while decoding process, and the size of digital contents are invariant in the whole process. Experimental results with simulation confirmed that the modified codes keep compatibility with standard JPEG format, and revealed the proposed method is suitable for DRM in the network distribution system.