Abstract: Hashes are short summaries or signatures of data files which can be used to identify the file. Hashing multimedia content (audio, video, images) is difficult because the hash of original content and processed (e.g. compressed) content may differ significantly. The disclosed method generates robust hashes for multimedia content, for example, audio clips. The audio clip is divided (12) into successive (preferably overlapping) frames. For each frame, the frequency spectrum is divided (15) into bands. A robust property of each band (e.g. energy) is computed (16) and represented (17) by a respective hash bit. An audio clip is thus represented by a concatenation of binary hash words, one for each frame. To identify a possibly compressed audio signal, a block of hash words derived therefrom is matched by a computer (20) with a large database (21). Such matching strategies are also disclosed.

Abstract: A method and a system for embedding a watermark in a media signal x are disclosed. The method comprises providing an at least partially encrypted media signal cx of said media signal x, wherein encryption is performed using a first encryption key k1; providing an at least partially encrypted watermark signal cw, wherein encryption is performed using a second encryption key k2; combining the at least partially encrypted media signal cx and the at least partially encrypted watermark signal cw in a combiner to obtain an encrypted combined media signal cy; and obtaining a decrypted watermarked media signal y by decrypting said encrypted combined media signal cy using a third decryption key k3. The present invention provides a framework for secure watermark embedding within untrusted devices.