System and method for partially encrypted multimedia stream

• US 20040073917A1
• Filed: 03/31/2003
• Published: 04/15/2004
• Est. Priority Date: 01/02/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Pedlow, Leo M. Jr., Candelore, Brant, Derovanessian, Henry
• Granted Patent: US 7,215,770 B2
• Time in Patent Office: Days
• US Class Current: 725/31
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 9/08 Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords network architectures or network communication protocols for supporting key management in a packet data network H04L63/06
• CPC Class Codes: H04N 21/23608 Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/23897 by partially encrypting, e.g. encrypting only the ending portion of a movie
• CPC Class Codes: H04N 21/43607 Interfacing a plurality of external cards, e.g. through a DVB Common Interface [DVB-CI]
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

A multimedia stream head end includes a legacy conditional access (CA) device that fully encrypts the stream using legacy keys. A copy of the stream is sent to a secondary CA device that encrypts only critical packets in the stream using secondary keys to render a partially encrypted stream. The critical packets in the fully encrypted stream from the legacy CA device are obtained and inserted next to the corresponding critical packets in the partially encrypted stream. Thus, only critical packets are encrypted, with encrypted versions being generated by both the legacy CA and secondary CA without the legacy CA knowing which of the packets that it encrypts are “critical”.

Claims

1. A method for multimedia transmission, comprising:

generating a copy of a multimedia stream to render first and second clear streams having identical predetermined portions;

sending the first clear stream to a first conditional access (CA) component to encrypt the entire first clear stream to render a completely encrypted stream;

obtaining encrypted versions of the predetermined portions from the completely encrypted stream;

using the second clear stream, encrypting the predetermined portions using a second CA component to render a partially encrypted stream; and

inserting the encrypted predetermined portions obtained from the completely encrypted stream into the partially encrypted stream for transmission thereof.

2. The method of claim 1, comprising transmitting the partially encrypted stream to plural set-top boxes over cable.

3. The method of claim 1, comprising wirelessly broadcasting the partially encrypted stream to plural receivers.

4. The method of claim 1, wherein the first CA component is a legacy component provided by an incumbent.

5. The method of claim 1, comprising determining locations of the predetermined portions at least in one of the streams using corresponding offsets from at least one packet identifier (PID).

6. The method of claim 5, wherein the offsets are in integral numbers of packets from at least one PID.

7. The method of claim 5, wherein the offsets are used for identifying the locations of the encrypted predetermined portions in the completely encrypted stream for obtaining them and inserting them into the partially encrypted stream.

8. The method of claim 1, wherein the encrypted predetermined portions obtained from the completely encrypted stream are inserted adjacent to the predetermined portions encrypted using the second CA component in the partially encrypted stream.

9. A system for dual partial encryption of a digital data stream, comprising:

means for copying the stream to render first and second streams;

first conditional access (CA) means for encrypting only critical portions of the first stream to render a partially encrypted stream;

legacy CA means for encrypting the entire second stream to render a substantially fully encrypted stream; and

means for combining only critical portions from the fully encrypted stream with the partially encrypted stream.

10. The system of claim 9, further comprising means for transmitting the partially encrypted stream.

11. The system of claim 9, comprising means for transmitting the partially encrypted stream to plural set-top boxes over cable.

12. The system of claim 9, comprising means for wirelessly broadcasting the partially encrypted stream to plural receivers.

13. The system of claim 9, comprising means for determining locations of the critical portions at least in one of the streams using corresponding offsets from at least one packet identifier (PID).

14. The system of claim 13, wherein the offsets are in integral numbers of packets from at least one PID.

15. The system of claim 13, wherein the offsets are used for identifying the locations of the critical portions from the fully encrypted stream.

16. The system of claim 9, wherein the critical portions generated by the legacy CA means are adjacent, in the partially encrypted stream, to critical portions generated by the first CA means.

17. A system for use in a digital stream transmitter head end having a legacy conditional access (CA) device, comprising:

at least a system CA device encrypting at least predetermined portions of a first version of a stream; and

a reconstitution component combining, into a stream, the predetermined portions from the system CA device and the predetermined portions obtained from a full encryption of a second version of the stream, the full encryption being generated by the legacy CA device.

18. The system of claim 17, wherein the predetermined portions obtained from the full encryption generated by the legacy CA device represent the same information as the predetermined portions encrypted by the system CA device, and the stream into which the predetermined portions are combined is the first version of the stream.

19. The system of claim 18, wherein the head end transmits the partially encrypted stream over cable.

20. The system of claim 18, wherein the head end wireless broadcasts the partially encrypted stream.

21. The system of claim 18, comprising at least one critical packet locator determining offsets of at least some predetermined portions from at least one packet identifier (PID).

22. The system of claim 21, wherein the offsets are in integral numbers of packets from at least one PID.

23. The system of claim 21, wherein the reconstitution component uses the offsets to insert, into the partially encrypted stream, the predetermined portions obtained from the full encryption such that the predetermined portions obtained from the full encryption are adjacent to the predetermined portions of the first version in the partially encrypted stream.

24. The system of claim 17, further comprising at least one buffer temporarily holding the first version of the stream.

25. The system of claim 21, further comprising at least one data structure storing the offsets.