Fast public-key watermarking of compressed video

Most watermarking techniques for images and video techniques involve a private key, for example a pseudo-noise signal, which is required for retrieval of the watermark information. This key is typically not public, because publication of the key would give rise to attacks on the watermark. In practical systems, however, watermarking techniques are required that enable public decoding of the watermark. In this paper, an extension of spread-spectrum watermarking is presented which enables public decoding and verification of the watermark, without at the same time giving the possibility of removing the watermark. The underlying idea, is to make only parts of the pseudo-noise key public. The scheme can be combined with a fast compressed-domain embedding technique to facilitate on-the-fly compressed-domain public-key watermarking.