Conditional access apparatus and method
First Claim
1. A method of processing 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 being decryptable with successive decryption information from the messages, the method comprising storing the stream of encrypted data;
- storing items with decryption information for the encrypted data independently retrievable from the stream;
storing synchronization information linking respective points in the stored stream of encrypted data to respective ones of the items with decryption information;
replaying a stored part of the stream of encrypted data;
retrieving the items with decryption information for the points in said stored part during said replaying;
combining the retrieved items with decryption information with the stream during replay at times selected under control of the synchronization information.
2 Assignments
0 Petitions
Accused Products
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. The stream is fed to a decoder and the decryption information is combined with the stream by feeding the decryption information to a secure device, which in response to the decryption information feeds control words to the decoder.
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Citations
12 Claims
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1. A method of processing 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 being decryptable with successive decryption information from the messages, the method comprising
storing the stream of encrypted data; -
storing items with decryption information for the encrypted data independently retrievable from the stream;
storing synchronization information linking respective points in the stored stream of encrypted data to respective ones of the items with decryption information;
replaying a stored part of the stream of encrypted data;
retrieving the items with decryption information for the points in said stored part during said replaying;
combining the retrieved items with decryption information with the stream during replay at times selected under control of the synchronization information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 12)
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8. A conditional access apparatus for processing 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 being decryptable with successive decryption information from the messages, the apparatus comprising
storage means, the apparatus being arranged to store the stream of encrypted data in the storage means, as well as storing items with decryption information for the encrypted data independently retrievable from the stream, and storing synchronization information linking respective points in the stored stream of encrypted data to respective ones of the items with decryption information; -
a replay unit for replaying a stored part of the stream of encrypted data;
a retrieval unit arranged to retrieve the items with decryption information for the points in said stored part from the storage means, and to feed said items to the replay unit during said replaying;
a secure device, arranged to generate control words under control of the decryption information and to feed the control words to the replay unit to decrypt the items;
a synchronization unit arranged to combine the retrieved items with decryption information with the stream during replay at times selected under control of the synchronization information by feeding the decryption information to the secure device at the selected times, for generating the control words. - View Dependent Claims (9, 10, 11)
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Specification