Public key watermarking for authentication of CSG models

This paper describes a new method for watermarking CSG models. The method is intended for verification purposes and is based on digital signature techniques. It computes the watermark from selected attributes of the model and stores it in one or more places into the model itself. Because it does not alter the original model structure, it is compatible with copyright protection watermarking techniques and can be used many times to have a multiple watermark: moreover, no pre-processing phase is required before using the model. The verification phase requires a small a priori data knowledge, and no secret at all. A distributed watermark extension of the schema shows strong localisation capabilities. Watermark data can be stored in control nodes or in comments, and we discuss the two possibilities for their characteristics of storage requirements, localisation capability, and rendering speed. The algorithm is very fast both in casting and verifying the watermark. This method can be easily used with public key certificates and thus is ready to he integrated in any existing Public Key Infrastructure. Our non-distributed test implementation is also described. (C) 2000 Elsevier Science Ltd. All rights reserved.