Abstract: A broadcast data stream that contains a stream of encrypted data and a stream of messages. Data in successive segments of the stream of encrypted data is decryptable with successive decryption information from the messages. The stream of encrypted data is stored upon reception. The items with decryption information for the encrypted data are stored independently retrievable from the stream. Additionally synchronization information is generated and stored to link respective points in the stored stream of encrypted data to respective ones of the items with decryption information. During replay of a stored part of the stream of encrypted data the items with decryption information for the points in said stored part are retrieved. The retrieved items with decryption information are combined with the stream during replay at times selected under control of the synchronization information.

Abstract: In a file system and in particular in a real-time file system it might not be possible to write a data to disc completely. Nevertheless the data that has been written to disc is often still useful, for example in case of an MPEG-stream. Marking parts of the file defective in the file system providing meta-data enables an application to perform application specific error correction or error concealment By using a filter driver, the file system can be extended with this error handling, thus making this functionality available to every application.

Abstract: A secure device capable of selectively enabling decryption of units of information is used to provide access to a stream of units of encrypted information. Each unit is linked to a time-stamp. An entitlement management message entitles the secure device to enable decryption of units of information that are linked to time-stamps with values in a specified range. The range has a starting point substantially prior to a current time value of the time stamps distributed concurrent the entitlement message. In an embodiment the stream is distributed to a plurality of subscribers, each with an own secure device. The distance of the starting point to the current time value for each subscriber is selected dependent on subscription information for the subscriber.