| 摘要 |
<p>A method for generating digital watermarks and for exchanging data containing such watermarks is described. It is based on a watermarking technique which is robust against image transformation techniques such as compression, rotation, translation, scaling and/or change of proportion. It uses modulation of the magnitude components in Fourier space and adds/reads a template in the log-polar or log-log transform of the magnitude components. The template is used for analyzing scaling and rotation or change of proportion. In addition, the system applies cryptographic protocols and public key techniques for both, encoding the watermark and transferring watermarked data. Preferably, an author (CH) 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 (CCC) before transmitting the data to a receiving party (B). The latter can use the public key infrastructure (I) for verifying autorship. Data exchanged by the parties are encrypted using the cryptographic keys. In addition, image (video) originality verification is supported by the same asymmetric key pair as for content protection and for copyright protection.</p> |
