Abstract: A method of content sub-item substitution is described. The method includes: receiving from a headend a description of a plurality of virtual channels, the description defining each virtual channel on the basis of one or more metadata attributes associated with that virtual channel; receiving one or more content sub-item substitution opportunities for each virtual channel, each content sub-item substitution opportunity specifying one or more content sub-items for use in the content sub-item substitution; and receiving and recording a content item, the content item including metadata associated with the content item and one or more substitutable content sub-items.

Abstract: A method of decrypting a scrambled digital data item at a client is disclosed, the method including: receiving actual control messages at the client, wherein each actual control message includes control word generating information for generating a control word associated with the actual control message; storing the actual control messages at the client; receiving the scrambled digital data item at the client independently of the actual control messages, wherein the scrambled digital data item includes a plurality of segments of scrambled digital data, each segment of scrambled digital data being associated with one of the actual control messages and being scrambled with the control word associated with the one of the actual control messages, and wherein the scrambled digital data item further includes a plurality of reference control messages, each segment of scrambled digital data comprising one of the reference control messages, each of the reference control messages including a control message reference va

Abstract: A method of assessing security of information technology. A list of security aspects is accessed. An information technology is assessed for each security aspect in the list.