METHOD AND APPARATUS FOR WATERMARKING AND AUTHENTICATING DATA

摘要

A method and apparatus for watermarking and authenticating data. Features codes are derived from multimedia data (e.g., image data) and used to derive a quasi-random watermark and an encrypted signature. In two stages of watermarking, the quasi-random watermark and the signature are embedded in the multimedia data to derive watermarked data. In an authentication procedure, the watermarked data are authenticated by newly deriving the feature codes, extracting the watermarks, and determining whether the extracted watermarks correspond to the newly derived feature codes. In addition, the embedded signature is extracted from the data and decrypted. The newly derived feature codes are used to derive data which is compared to the decrypted signature. The user of the above procedures can select a desired authentication strength based upon the percentage of the multimedia data used to derive the feature codes.