Partial Dual-Encryption Using Program Map Tables

• US 20090147954A1
• Filed: 01/13/2009
• Published: 06/11/2009
• Est. Priority Date: 11/21/2003
• Status: Active Grant

• Current Assignee: Tech 5 SAS
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Woodward,, William D. JR., Evans, Jonathan Bradford, Wasilewski, Anthony J., Pinder, Howard
• Granted Patent: US 8,396,216 B2
• Time in Patent Office: Days
• US Class Current: 380/216
• CPC Class Codes: H04N 21/23476 by partially encrypting, e.g. encrypting the ending portion of a movie
• CPC Class Codes: H04N 21/2362 Generation or processing of Service Information [SI]
• 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 21/44055 by partially decrypting, e.g. decrypting a video stream that has been partially encrypted
• CPC Class Codes: H04N 7/163 by receiver means only
• 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

Systems and method for partial encryption are disclosed. One example method comprises: creating a program association table to include a first program number which identifies a program encrypted in accordance with a first encryption scheme, and a second program number which identifies the same program encrypted in accordance with a second encryption scheme; and creating a program map table for the same program to include first audio and video identifiers associated with the first encryption scheme and second audio and video identifiers associated with the second encryption scheme.

Claims

1. A method for encoding and encrypting a program in at least two distinct partial-encrypted streams, the method comprising:

creating a program association table to include a first program number which identifies a program encrypted in accordance with a first encryption scheme, and a second program number which identifies the same program encrypted in accordance with a second encryption scheme; and

creating a program map table for the same program to include first audio and video identifiers associated with the first encryption scheme and second audio and video identifiers associated with the second encryption scheme.

2. The method of claim 1, the creating the program map table further comprising:

creating the program map table to include conditional access descriptors associated with the second encryption scheme.

3. The method of claim 1, further comprising:

multiplexing the program map table with a clear portion of the program to produce a single stream; and

transmitting the single stream to a plurality of set-tops.

4. The method of claim 1, the creating the program map table further comprising:

creating the program map table to include third audio and video identifiers identifying a clear portion of the same program.

5. The method of claim 4, further comprising:

encrypting the program map table according to the first encryption scheme.

6. The method of claim 1, further comprising:

creating another program map table for the same program to include the first audio and video identifiers associated with the first encryption scheme but not to include the second audio and video identifiers associated with the second encryption scheme.

7. The method of claim 6, the creating the another program map table further comprising:

creating the another program map table to include conditional access descriptors associated with the first encryption scheme.

8. The method of claim 6, further comprising:

multiplexing the program map table with the another program map table and with a clear portion of the program to produce a single stream; and

transmitting the single stream to a plurality of set-tops.

9. The method of claim 6, further comprising:

encrypting the another program map table according to the second encryption scheme.

10. A communication system for encoding and transmitting a partial dual-encrypted program stream, the system comprising:

a device for providing a clear program stream and a first encrypted program stream in accordance with a first encryption scheme, wherein the clear program stream and the first encrypted program stream each have associated program map tables, each program map table referencing a plurality of programs, wherein at least one of the plurality of programs is provided in both the clear program stream and the first encrypted program stream;

a first demultiplexer for demultiplexing the plurality of programs in the clear program stream and providing each demultiplexed program in the clear program stream to an output of the first demultiplexer;

a second demultiplexer for demultiplexing the plurality of programs in the first encrypted program stream and providing each demultiplexed program in the first encrypted program stream to an output of the second demultiplexer; and

a plurality of identifier devices, each identifier device receiving a particular one of the demultiplexed programs of the clear program stream and receiving the same particular one of the demultiplexed programs of the first encrypted program stream, each identifier device identifying critical packets of the particular one of the demultiplexed programs of the clear program stream, for encryption by a second encryption scheme.

11. The communication system of claim 10, further comprising a multiplexer for multiplexing the identified critical packets, after encryption by the second encryption scheme, with corresponding critical packets in the first encrypted program stream.

12. The communication system of claim 11, wherein the multiplexer provides a single partial dual-encrypted program stream by further multiplexing non-critical packets of the particular one of the demultiplexed programs of the clear program stream, the second encrypted identified critical packets after encryption by the second encryption scheme, and corresponding critical packets in the first encrypted program stream.

13. The communication system of claim 10, each identifier device further comprising:

a first buffer for buffering the particular one of the demultiplexed programs of the first encrypted program stream;

a second buffer for buffering the same particular one of the demultiplexed programs of the clear program stream; and

a packet comparator for ensuring audio and video packet identifiers for each referenced program are aligned in the particular one of the demultiplexed programs of the first encrypted program stream as compared to the particular one of the demultiplexed programs of the clear program stream.

14. The communication system of claim 13, wherein the packet comparator examines a continuity counter field to determine whether or not the audio and video packet identifiers for each referenced program are aligned.

15. The communication system of claim 10, each identifier device further comprising a critical packet selector for identifying and selecting the critical packets of the particular one of the demultiplexed programs of the clear program stream, and for allowing the identified critical packets of the particular one of the demultiplexed programs of the clear program stream to pass and for dropping the corresponding critical packet of the particular one of the demultiplexed programs of the first encrypted program stream.

16. The communication system of claim 10, each identifier device further comprising a critical packet selector for identifying and selecting the critical packets of the particular one of the demultiplexed programs of the clear program stream, and for dropping non-critical packets of the particular one of the demultiplexed programs of the clear program stream, and for passing the corresponding non-critical packets of the particular one of the demultiplexed programs of the first encrypted program stream.

17. The communication system of claim 10, further comprising:

an encryptor performing the second encryption scheme on the identified critical packets to produce a second encrypted program; and

each identifier device further comprising a remapper for encoding the program map table for the first encrypted program stream, and the program map table for the clear program stream and another program map table which includes audio and video packet identifiers for each program number of the second encrypted program.

18. A communication system for encoding and transmitting a partial dual-encrypted program stream, the communication system comprising:

a first encryptor for receiving a clear program stream and encrypting a plurality of programs carried in the clear program stream according to a first encryption scheme;

a second encryptor for receiving the clear program stream and encrypting the plurality of programs carried in the clear program stream according to a second encryption scheme;

a first demultiplexer for demultiplexing the plurality of program streams encrypted according to the first encryption scheme to produce a plurality of first encrypted programs;

a second demultiplexer for demultiplexing the plurality of program streams encrypted according to the second encryption scheme to produce a plurality of second encrypted programs;

a third demultiplexer for demultiplexing the clear program stream to produce a plurality of clear programs; and

a plurality of identifier devices, each identifier device receiving a particular one of the programs from the plurality of first encrypted programs and receiving the same particular one of the programs from the plurality of second encrypted programs and receiving the same particular one of the programs from the plurality of clear programs, wherein the particular program received by each identifier device differs in a form of encryption, each identifier device configured to;

identify critical packets in the particular program received from the plurality of clear programs; and

responsive to the identification, drop the identified critical packets in the particular program received from the plurality of the clear programs and pass corresponding critical packets in the particular program received from the plurality of first encrypted programs and in the particular program received from the plurality of second encrypted programs.

19. The communication system of claim 18, at least one of the identifier devices further comprising:

a multiplexer for multiplexing the passed packets, the packets encrypted according to the first encryption scheme, and the packets encrypted according to the second encryption scheme.

20. The communication system of claim 18, each identifier device further comprising:

a remapper for encoding a program map table of the particular program in the plurality of clear programs, a program map table of the particular program received from the plurality of first encrypted programs, and a program map table including audio and video packet identifiers for each program of the plurality of second encrypted programs.