Method and system for encrypting and decrypting a transport stream using multiple algorithms

• US 20080123859A1
• Filed: 11/27/2006
• Published: 05/29/2008
• Est. Priority Date: 11/27/2006
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Mamidwar, Rajesh
• Granted Patent: US 8,213,602 B2
• Time in Patent Office: Days
• US Class Current: 380/278
• CPC Class Codes: H04L 9/0625 with splitting of the data block into left and right halves, e.g. Feistel based algorithms, DES, FEAL, IDEA or KASUMI
• CPC Class Codes: H04L 9/0631 Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms
• CPC Class Codes: H04L 9/0827 involving distinctive intermediate devices or communication paths network architectures or network communication protocols using different networks H04L63/18

Abstract

There is provided a method for encrypting a data stream using multiple algorithms. In one embodiment, a first portion of the data stream is encrypted with a first algorithm utilizing a first key to generate a first encrypted portion. The first algorithm can be, for example, a Triple Data Encryption Algorithm (TDEA). Data indicating the first algorithm and the first key is then transmitted. Then, the first encrypted portion of the data stream is transmitted. Thereafter, a second portion of the data stream is encrypted with a second algorithm utilizing a second key to generate a second encrypted portion. The second algorithm can be, for example, a Single Data Encryption Algorithm (SDEA). Next, data indicating the second algorithm and the second key is transmitted. Thereafter, the first encrypted portion of the data stream is transmitted.

Claims

1. A method for encrypting a data stream, said method comprising:

encrypting a first portion of said data stream with a first algorithm utilizing a first key to generate a first encrypted portion;

transmitting data indicating said first algorithm and said first key;

transmitting said first encrypted portion;

encrypting a second portion of said data stream with a second algorithm utilizing a second key to generate a second encrypted portion;

transmitting data indicating said second algorithm and said second key; and

transmitting said second encrypted portion.

2. The method of claim 1 wherein said first and second encrypted portions comprise respective first and second pluralities of encrypted transport packets, wherein a first parity of said first key is included in each of said first plurality of encrypted transport packets, and a second parity of said second key is included in each of said second plurality of encrypted transport packets.

3. The method of claim 1 wherein said data stream is an MPEG-2 transport stream.

4. The method of claim 1 wherein said first and second algorithms is each one of a Single Data Encryption Algorithm (SDEA), a Triple Data Encryption Algorithm (TDEA), a Common Scrambling Algorithm (CSA), or an Advanced Encryption Standard (AES) Algorithm.

5. The method of claim 1 wherein said data indicating said first algorithm and said first key and said data indicating said second algorithm and said second key are transmitted through a different channel than said first and second encrypted portions.

6. The method of claim 1 wherein said first and second encrypted portions are stored in a storage device.

7. The method of claim 1 wherein said data indicating said first algorithm and said first key is included in a first key packet and said data indicating said second algorithm and said second key is included in a second key packet

8. A method for decrypting an encrypted data stream, said method comprising:

receiving data indicating a first algorithm and a first key;

receiving a first encrypted portion of said encrypted data stream;

decrypting said first encrypted portion using said first algorithm and said first key;

receiving data indicating a second algorithm and a second key;

receiving a second encrypted portion of said encrypted data stream;

decrypting said second encrypted portion using said second algorithm and said second key.

9. The method of claim 8 wherein said first and second encrypted portions comprise respective first and second pluralities of encrypted transport packets, wherein a first parity of said first key is included in each of said first plurality of encrypted transport packets, and a second parity of said second key is included in each of said second plurality of encrypted transport packets.

10. The method of claim 8 wherein said encrypted data stream is an encrypted MPEG-2 transport stream.

11. The method of claim 8 wherein said first and second algorithms is each one of a Single Data Encryption Algorithm (SDEA), a Triple Data Encryption Algorithm (TDEA), a Common Scrambling Algorithm (CSA), or an Advanced Encryption Standard (AES) Algorithm.

12. The method of claim 8 wherein said data indicating said first algorithm and said first key and said data indicating said second algorithm and said second key are received through a different channel than said first and second encrypted portions.

13. The method of claim 8 wherein said first and second encrypted portions are provided by a storage device.

14. The method of claim 8 wherein said data indicating said first algorithm and said first key is included in a first key packet and said data indicating said second algorithm and said second key is included in a second key packet

15. An encryption device for encrypting a data stream, said device comprising:

a data stream receiver for receiving said data stream;

a key generation module for generating first and second keys;

an algorithm controller module comprising a first algorithm and a second algorithm;

wherein said algorithm controller module is configured to encrypt a first portion of said data stream with said first algorithm utilizing said first key and to encrypt a second portion of said data stream with said second algorithm utilizing said second key.

16. The method of claim 15 wherein said data stream is a data stream to a handheld device.

17. The method of claim 15 wherein said first and second algorithms is each one of a Single Data Encryption Algorithm (SDEA), a Triple Data Encryption Algorithm (TDEA), a Common Scrambling Algorithm (CSA), or an Advanced Encryption Standard (AES) Algorithm.

18. The method of claim 15 wherein said encryption device is configured to generate data indicating said first algorithm and said first key and data indicating said second algorithm and said second key.

19. The method of claim 15 wherein said data indicating said first algorithm and said first key is transmitted in a first key packet and said data indicating said second algorithm and said second key is transmitted in a second key packet.

20. The method of claim 15 wherein said encryption device is configured to transmit said first and second encrypted portions to a storage device.