ENCODING AND DETECTING APPARATUS

摘要

An encoding data processing apparatus generates a marked copy of a video material item by representing a payload data word as a code word and embedding the code word into a copy of the video material item. The apparatus comprises a code word generator including a pre-processor and an encryption processor. The preprocessor is operable to divide the payload word into a plurality of parts, to form a plurality of initial values from the plurality of parts, each of the initial values being formed by adding parts of the payload data word to each initial value successively starting with the first part added to the first initial value, and adding the first and second to the second initial value so that each subsequent initial value includes all the parts of the payload data word of those of the previous initial values in addition to a new part of the payload data word. The encryption processor is operable to receive each of the initial values and to generate an encrypted data stream from each of the initial values using a payload encryption key. A combiner is operable to combine the encrypted payload data word with the video material item. The encrypted data streams are thereby provided with improved orthogonality, which can assist in the detection of each of the encrypted data streams by correlation. Furthermore, the likelihood of an attacker being able to discover, alter or destroy the payload data word in the material item is reduced.