| 摘要 |
An encoding data processing apparatus is arranged to generate a marked copy of an item of material by introducing at least one code word into a copy of the material item, the code word being arranged to identify a payload data word. The encoding apparatus comprises an encryption circuit operable to receive a payload encryption key and to receive the payload data word, and to encrypt the payload data word using the payload encryption key. A pseudo random number generator receives the encrypted payload data and a finger print key and generates the code word having a plurality of code word coefficients using the encrypted payload as a seed for the pseudo random number generator and the finger print key. A combiner combines the code word with the material to form the marked copy of the material item. The encoding apparatus may form part of a media terminal for marking material items with the code words, when the material items are to be reproduced. A more secure system for reproducing watermarked material can be formed using the encoding apparatus in which the payload data is encrypted and used as a seed for the pseudo random number generator with the finger print key to generate the code word coefficients. The code word is thereby generated from a finger print key and an encrypted seed, which provides an improved level of security against an attack aimed at compromising correction detection of a code word in a mark material item. |
