Supported by the National High-Tech Research and Development Plan of China under Grant No.2001AA114010 (国家高技术研究发展计划(863)
Watermark technology has been developed to tackle the problem of unauthorized copying and distribution of digital data. Several different schemes have been proposed in the last few years, but most of them are symmetric, i.e., the key used for watermark embedding is just the same used for watermark detection. However, in many applications, an asymmetric scheme is needed, where the secrete information used to detect the watermark is not enough to modify, counterfeit or remove the watermark. In this paper, some watermark verification protocols based on bit commitment and zero knowledge proof are proposed. The ownership prover insert the watermark into the host signal using symmetric watermark technology based on spread spectrum. The watermark detect key is sent to the verifier hiding in bit commitment. By the interactive protocol between the prover and the verifier, the verifier can extract the embedded watermark, but he can not modify, counterfeit or remove it. Protocols are proposed to verify one watermark bit and several watermark bits respectively. Those protocols can be used to verify the watermark information inserted into image, audio and video using spread spectrum watermark technology.