Rapid decryption of data by key synchronization and indexing

• US 20040268117A1
• Filed: 08/13/2003
• Published: 12/30/2004
• Est. Priority Date: 06/25/2003
• Status: Active Grant

• Current Assignee: Nytell Software LLC (Intellectual Ventures LLC)
• Original Assignee: Wegener Communications, Inc. (Wegener Corporation)
• Inventors: Pelkey, Gary L.Pelkey, Kennedy, Kevin, Olivier, Steve, Placek, David M.
• Granted Patent: US 7,206,411 B2
• Time in Patent Office: Days
• US Class Current: 713/150
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04H 60/23 using cryptography, e.g. encryption, authentication, key distribution
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/26613 for generating or managing keys in general key distribution for secret or secure communication involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] H04L9/083; network support of key management H04L63/06; key management for network security in communication control or processing H04W12/04
• CPC Class Codes: H04N 21/454 Content or additional data filtering, e.g. blocking advertisements
• CPC Class Codes: H04N 21/6143 involving transmission via a satellite
• CPC Class Codes: H04N 21/63345 by transmitting keys key distribution for secret or secure communication H04L9/08; network support of key management H04L63/06
• 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 satellite broadcast conditional access system with key synchronization uses indexing of an authorization stream to quickly restart the decrypting process after short carrier fades and after carrier switches. The authorization stream includes cyphered seeds and index numbers which are sequentially sent to a group of receivers. The same authorization stream can also be broadcast multiple times to the group of receivers. A conditional access server selects a starting index number and increments the index number by a predefined value. The receivers have a memory to save the current index number for the authorization stream. Any receiver that loses its connection to the broadcast and thereafter reestablishes its connection can retrieve the latest index number being issued in the authorization stream and compare it with the stored index number. When the index numbers match or are within a defined threshold, the receiver will continue to decypher the seeds and decrypt the transport stream.

Claims

1. A method of encrypting data for rapid decryption, the method comprising the steps of:

sequentially generating a plurality of random numbers;

sequentially generating a plurality of index numbers respectively associated with said random numbers, wherein a first index number is initially generated and said index numbers increment by a predefined value; and

calculating a plurality of cyphered seeds according to a combination of each one of said random numbers and each one of said respectively associated index numbers.

2. The method according to claim 1, wherein said generating of said index numbers is further comprised of the step of randomly generating said first index number.

3. The method according to claim 1, further comprising the steps of:

sending said plurality of cyphered seeds and said corresponding index numbers from a server to at least one receiver; and

resending each one of said plurality of cyphered seeds and said corresponding index numbers from said server to said receiver, wherein a cyphered seed and index number pair is resent before sending a subsequent cyphered seed and index number pair.

4. The method according to claim 3, wherein said sending and resending steps further comprise the steps of:

sending a first flavored cyphered seed and index number pair;

resending said first flavored cyphered seed and index number pair;

sending a second flavored cyphered seed and index number pair;

resending said second flavored cyphered seed and index number pair; and

repeating said sending and resending steps for a plurality of first flavored cyphered seed and index number pairs and for a plurality of second flavored cyphered seed and index number pairs.

5. The method according to claim 3, further comprising the steps of:

decyphering said cyphered seed and index number pair;

storing said decyphered seed and index number pair in a memory;

repeating said decyphering and storing steps for a plurality of subsequent cyphered seed and index number pairs until an occurrence of a reset;

after said reset, decyphering a most recently received index number and comparing said most recently received index number with said stored index number; and

continuing with said decyphering and storing steps if said most recently received index number is within a defined tolerance of said stored index number.

6. The method according to claim 5, further comprising the steps of:

when a cyphered seed of a particular flavor is received, decyphered, and loaded to said receiver, setting a flavor seed flag to designate said flavor; and

when said receiver detects that a flavor in incoming encrypted transport streams changes to a new flavor, examining whether said flavor seed flag is set to correspond said new flavor for checking if said decyphered seed is valid to decrypt said incoming encrypted transport streams.

7. The method according to claim 5, further comprising the step of defining said tolerance of said stored index number to one.

8. The method according to claim 5, further comprising the steps of:

sending a group of cyphered seed and corresponding index number pairs from said server to a respective group of receivers during a flavor distribution period;

resending said group of cyphered seed and corresponding index number pairs to said respective group of receivers during said flavor distribution period; and

repeating said sending and resending steps for a plurality of subsequent groups of cyphered seed and corresponding index number pairs to said respective group of receivers.

9. The method according to claim 8, wherein said repeating step further comprises the step of switching between a first flavor and a second flavor.

10. The method according to claim 8, further comprising the step of sending an authorization stream from said server to said group of receivers during said flavor distribution period, said authorization stream comprising said group of cyphered seed and corresponding index number pairs, a plurality of serial numbers corresponding to said respective group of receivers, a flavor indicator, and an encryption on/off message.

11. The method according to claim 10, further comprising the step of indicating to said group of receivers whether corresponding transport streams are encrypted according to said encryption on/off message.

12. The method according to claim 10, further comprising the step of generating a plurality of secret serial numbers according to a combination of a secret identification number and a serial number associated with each of said receivers.

13. The method according to claim 12, further comprising the step of allowing a customer controlling said group of receivers to generate said secret identification number unique to said customer.

14. The method according to claim 12, wherein said step for calculating a plurality of cyphered seeds is further comprised of the step of combining each one of said random numbers and said respectively associated index numbers with each one of said secret serial numbers.

15. A method of encrypting data for rapid decryption, the method comprising the steps of:

sequentially generating a plurality of random numbers;

sequentially generating a plurality of index numbers respectively associated with said random numbers, wherein a first index number is initially generated and said index numbers increment by a predefined value;

calculating a plurality of cyphered seeds according to a combination of each one of said random numbers, each one of said respectively associated index numbers, and a plurality of serial numbers respectively associated with a group of receivers;

sending a group of cyphered seed and corresponding index number pairs from a server to said group of receivers during a flavor distribution period;

resending said group of cyphered seed and corresponding index number pairs to said group of receivers during said flavor distribution period;

repeating said sending and resending steps for a plurality of subsequent groups of cyphered seed and corresponding index number pairs to said group of receivers.

extracting a cyphered seed using its serial number from said cyphered seed and index number pairs in each one of said receivers;

decyphering said cyphered seed and index number pairs in each one of said receivers;

storing said decyphered seed and index number pair in a memory of each one of said receivers;

repeating said decyphering and storing steps for a plurality of subsequent cyphered seed and index number pairs until an occurrence of a reset;

after said reset, decyphering a most recently received index number and comparing said most recently received index number with said stored index number; and

continuing with said decyphering and storing steps if said most recently received index number is within a defined tolerance of said stored index number.

16. The method according to claim 15, wherein said generating of said index numbers is further comprised of the step of randomly generating said first index number.

17. The method according to claim 15, further comprising the step of sending an authorization stream from said server to said group of receivers during said flavor distribution period, said authorization stream comprising said group of cyphered seed and corresponding index number pairs, said plurality of serial numbers corresponding to said respective group of receivers, a flavor indicator, and an encryption on/off message.

18. The method according to claim 15, further comprising the step of generating a plurality of secret serial numbers according to a combination of a secret identification number and a serial number associated with each of said receivers.

19. The method according to claim 18, further comprising the step of allowing a customer controlling said group of receivers to generate said secret identification number unique to said customer.

20. The method according to claim 18, wherein said secret serial numbers are used as said serial numbers in calculating said cyphered seeds.

21. The method according to claim 15, further comprising the steps of:

receiving, decyphering, and loading at least one of said cyphered seeds of an indicated flavor in each one of said receivers;

respectively setting a flavor seed flag in each one of said receivers to designate said indicated flavor;

detecting a flavor change associated with a new flavor in incoming encrypted transport streams in each one of said receivers;

determining whether said flavor seed flag is set to correspond with said new flavor and whether said decyphered seed is valid in each one of said receivers; and

decrypting said incoming encrypted transport streams in each one of said receivers when said decyphered seed is valid.

22. The method according to claim 15, further comprising the step of defining said tolerance of said stored index number to one.

23. A system for encrypting and decrypting data, comprising:

means for sequentially generating a plurality of random numbers and a plurality of index numbers respectively associated with said random numbers, wherein a first index number is initially generated and said index numbers increment by a predefined value;

means for calculating a plurality of cyphered seeds according to a combination of each one of said random numbers, each one of said respectively associated index numbers, and a plurality of serial numbers respectively associated with a group of receivers;

means for sending a group of cyphered seed and corresponding index number pairs from a server to said group of receivers during a flavor distribution period, and resending said group of cyphered seed and corresponding index number pairs to said group of receivers during said flavor distribution period;

means for extracting a cyphered seed and corresponding index number from said cyphered seed and index number pairs, wherein at least one of said serial numbers is used to extract said cyphered seed;

a decrypter in operative communication with said extracting means receives said extracted cyphered seed and said index number and decyphers said cyphered seed into a decyphered seed;

a memory device in operative communication with said decrypter receives and stores said decyphered seed and index number;

means for setting a reset command and thereafter comparing a new index number with said stored index number according to a defined tolerance.

24. The system according to claim 23, wherein said first index number is further comprised of a randomly generated number.

25. The system according to claim 23, wherein said means for generating said random numbers and said index numbers is comprised of a server with a computer processor.

26. The system according to claim 23, wherein said means for calculating said cyphered seeds is comprised of an encryption function in said server.

27. The system according to claim 23, wherein said means for sending and resending said cyphered seed and index number pairs from said server to said receivers is comprised of a multiplexer controlled by said server.

28. The system according to claim 23, wherein said means for extracting said cyphered seed, setting said reset command, and returning to said steady state operation is comprised of a host microprocessor in at least one of said receivers.

29. The system according to claim 23, wherein said defined tolerance of said stored index number is one.

30. The system according to claim 23, wherein said plurality of serial numbers are further comprised of a combination of a secret identification number, and wherein said secret identification number is unique to a customer controlling said group of receivers.

31. A server for encrypting data, comprising:

means for sequentially generating a plurality of random numbers and a plurality of index numbers respectively associated with said random numbers, wherein a first index number is initially generated and said index numbers increment by a predefined value;

means for calculating a plurality of cyphered seeds according to a combination of each one of said random numbers and each one of said respectively associated index numbers; and

means for sending a group of cyphered seed and corresponding index number pairs from a server to a respective group of receivers during a flavor distribution period, and resending said group of cyphered seed and corresponding index number pairs to said respective group of receivers during said flavor distribution period.

32. The system according to claim 31, wherein said first index number is further comprised of a randomly generated number.

33. The system according to claim 31, wherein said cyphered seeds are further comprised according to a combination of said random numbers and said index numbers with a plurality of serial numbers respectively associated with said group of receivers.

34. The system according to claim 33, wherein said plurality of serial numbers are further comprised of a combination of a secret identification number, and wherein said secret identification number is unique to a customer controlling said group of receivers.

35. An integrated receiver decoder for decrypting data, comprising:

means for extracting a cyphered seed and a corresponding index number from a group of cyphered seed and index number pairs;

wherein a plurality of serial numbers are used to generate a plurality of cyphered seeds and wherein at least one of said serial numbers is used to extract said cyphered seed;

a decrypter in operative communication with said extracting means receives said extracted cyphered seed and said corresponding index number and decyphers said cyphered seed into a decyphered seed;

a memory device in operative communication with said decrypter receives and stores said decyphered seed and index number; and

means for setting a reset command and thereafter comparing a new index number with said stored index number according to a defined tolerance.

36. The system according to claim 35, wherein said defined tolerance of said stored index number is one.