A proposal of digital rights management based on incomplete cryptography using invariant Huffman code length feature

Digital rights management (DRM) system is a promising technique to allow copyrighted content to be commercialized in digital format without the risk of revenue loss due to piracy. However, traditional DRMs are achieved with individual function modules of cryptography and watermarking. Therefore, all digital contents are temporarily disclosed in perfect condition via decryption process in the user-side risking illegal redistribution. This paper describes the basic idea of a novel DRM method composed of an incomplete cryptography using invariant Huffman code length feature and the user identification mechanism to control the quality of digital contents. The proposed incomplete cryptography consists of two processes: the incomplete encoding and the incomplete decoding. These processes are presented by randomly selecting the coefficients that belong to the same category or different category of Huffman code. In our scheme, the copyright information is embedded into the decoded content during the decoding process, and the size of digital contents are invariant during the process. Experimental results with simulation confirmed that the modified codes are compatible with standard JPEG format, and revealed the proposed method to be suitable for DRM in the network distribution system. © 2013 Springer-Verlag Berlin Heidelberg.