Method for generating digital watermarks and for exchanging data containing digital watermarks

摘要

A method for generating digital watermarks and for exchanging data containing such watermarks is described. The system is based on an watermarking technique which is robust against image transformation techniques such as compression, rotation, translation, and scaling. It uses modulation of the magnitude components in Fourier space and adds/reads a template in the log polar transform of the magnitude components. The template is used for analyzing scaling and rotation. In addition, the system applies cryptographic protocols and public key techniques for both, encoding the watermark and transferring watermarked data. Preferably, an author (ICH) encodes the watermark using an asymmetric cryptographic key pair provided by a public key infrastructure (PKI) and registers the watermarked data at a trusted registration party (ICO) before transmitting the data to a receiving party (IB). The latter can use the public key infrastructure (PKI) for verifying authorship. Transmission between the parties uses data protection provided by the cryptographic keys.