Protecting decrypted compressed content and decrypted decompressed content at a digital rights management client

• US 20020006204A1
• Filed: 06/27/2001
• Published: 01/17/2002
• Est. Priority Date: 06/27/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Marcus Peinado, Mukund Sankaranarayan, Paul England
• Inventors: England, Paul, Peinado, Marcus, Sankaranarayan, Mukund
• Granted Patent: US 7,239,708 B2
• Time in Patent Office: Days
• US Class Current: 380/269
• CPC Class Codes: G06F 21/109 by using specially-adapted hardware at the client
• CPC Class Codes: G06F 21/16 Program or content traceability, e.g. by watermarking
• CPC Class Codes: G06F 2221/2137 Time limited access, e.g. to a computer or data
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier

Abstract

Encrypted compressed content is produced by encrypting content based at least in part on a content key, and compressing the content based at least in part on the content key. Thus, the content key is employed to encrypt the content and also to compress the content. Similarly, decrypted decompressed content is produced from the encrypted compressed content by decrypting the content based at least in part on a content key, and decompressing the content based at least in part on the content key. Thus, the content key is employed to decrypt the content and also to decompress the content.

Claims

1. A computer system for receiving encrypted compressed content and for producing decrypted decompressed content based on the received encrypted compressed content, the system comprising:

a decryption element for decrypting the content based at least in part on a content key; and

a decompression element for decompressing the content based at least in part on the content key,

wherein the content key is employed to decrypt the content and also to decompress the content.

2. The computer system of claim 1 comprising:

a decryption element having an input for receiving the encrypted compressed content, the decryption element for decrypting the encrypted compressed content based at least in part on a content key to result in decrypted compressed content, and having an output for producing the decrypted compressed content; and

a decompression element having an input for receiving the decrypted compressed content, the decompression element for decompressing the decrypted compressed content based at least in part on the content key to result in decrypted decompressed content, and having an output for producing the decrypted decompressed content,

wherein a content thief that obtains the decrypted compressed content from the output of the decryption element cannot decompress the obtained decrypted compressed content by way of another decompression element without the content key.

3. The computer system of claim 1 wherein the decompression element has a number of adjustable parameters and wherein the decompression element employs the content key as at least one of the adjustable parameters.

4. The computer system of claim 3 wherein the decompression element includes an internal representation having DCT coefficients of macroblocks, and wherein the coefficients are de-scrambled and de-noised according to the content key.

5. The computer system of claim 3 wherein the decompression element includes a quantizer for performing a lossy quantization step, and wherein the quantizer is de-dithered according to the content key.

6. The computer system of claim 1 wherein the decryption element supplies the content key to the decompression element.

7. The computer system of claim 1 wherein the decompression element includes the decryption element.

8. The computer system of claim 1 wherein the decryption element includes the decompression element.

9. A computer system for receiving content and for producing encrypted compressed content based on the received content, the system comprising:

an encryption element for encrypting the content based at least in part on a content key; and

a compression element for compressing the content based at least in part on the content key,

wherein the content key is employed to encrypt the content and also to compress the content.

10. The computer system of claim 9 comprising:

a compression element having an input for receiving the content, the compression element for compressing the content based at least in part on a content key to result in compressed content, and having an output for producing the compressed content; and

an encryption element having an input for receiving the compressed content, the encryption element for encrypting the compressed content based at least in part on the content key to result in encrypted compressed content, and having an output for producing the encrypted compressed content,

wherein the encrypted compressed content from the output of the encryption element cannot be decompress without the content key.

11. The computer system of claim 9 wherein the compression element has a number of adjustable parameters and wherein the compression element employs the content key as at least one of the adjustable parameters.

12. The computer system of claim 11 wherein the compression element includes an internal representation having DCT coefficients of macroblocks, and wherein the coefficients are scrambled and noised according to the content key.

13. The computer system of claim 11 wherein the compression element includes a quantizer for performing a lossy quantization step, and wherein the quantizer is dithered according to the content key.

14. A method for receiving encrypted compressed content and for producing decrypted decompressed content based on the received encrypted compressed content, the method comprising:

decrypting the content based at least in part on a content key; and

decompressing the content based at least in part on the content key,

wherein the content key is employed to decrypt the content and also to decompress the content.

15. The method of claim 14 comprising:

decrypting the encrypted compressed content based at least in part on a content key to result in decrypted compressed content; and

decompressing the decrypted compressed content based at least in part on the content key to result in decrypted decompressed content,

wherein a content thief that obtains the decrypted compressed content cannot decompress the obtained decrypted compressed content without the content key.

16. The method of claim 14 wherein decompression is based on a number of adjustable parameters and wherein decompression comprises employing the content key as at least one of the adjustable parameters.

17. The method of claim 16 wherein decompression is based on an internal representation having DCT coefficients of macroblocks, and wherein decompression comprises de-scrambling and de-noising the coefficients according to the content key.

18. The method of claim 16 wherein decompression is based on a quantizer for performing a lossy quantization step, and wherein decompression comprises de-dithering the quantizer according to the content key.

19. A method for receiving content and for producing encrypted compressed content based on the received content, the method comprising:

encrypting the content based at least in part on a content key; and

compressing the content based at least in part on the content key,

wherein the content key is employed to encrypt the content and also to compress the content.

20. The method of claim 19 comprising:

compressing the content based at least in part on a content key to result in compressed content; and

encrypting the compressed content based at least in part on the content key to result in encrypted compressed content,

wherein the encrypted compressed content from the output of the encryption element cannot be decompress without the content key.

21. The method of claim 19 wherein compression is based on a number of adjustable parameters and wherein compression comprises employing the content key as at least one of the adjustable parameters.

22. The system of claim 21 wherein compression is based on an internal representation having DCT coefficients of macroblocks, and wherein compression comprises scrambling and noising the coefficients according to the content key.

23. The system of claim 21 wherein compression is based on a quantizer for performing a lossy quantization step, and wherein compression comprises dithering the quantizer according to the content key.

24. A computer-readable medium having computer-executable instructions thereon for receiving encrypted compressed content and for producing decrypted decompressed content based on the received encrypted compressed content, the instructions being organized into modules including:

a first module for decrypting the content based at least in part on a content key; and

a second module for decompressing the content based at least in part on the content key,

wherein the content key is employed to decrypt the content and also to decompress the content.

25. The medium of claim 24 comprising:

a first module for decrypting the encrypted compressed content based at least in part on a content key to result in decrypted compressed content; and

a second module for decompressing the decrypted compressed content based at least in part on the content key to result in decrypted decompressed content,

wherein a content thief that obtains the decrypted compressed content cannot decompress the obtained decrypted compressed content without the content key.

26. The medium of claim 24 wherein the second module decompresses based on a number of adjustable parameters and wherein the second module employs the content key as at least one of the adjustable parameters.

27. The medium of claim 26 wherein the second module decompresses based on an internal representation having DCT coefficients of macroblocks, and wherein the second module de-scrambles and de-noises the coefficients according to the content key.

28. The medium of claim 26 wherein the second module decompresses is based on a quantizer for performing a lossy quantization step, and wherein the second module de-dithers the quantizer according to the content key.

29. A computer-readable medium having computer-executable instructions thereon for receiving content and for producing encrypted compressed content based on the received content, the method comprising:

a first module for encrypting the content based at least in part on a content key; and

a second module for compressing the content based at least in part on the content key,

wherein the content key is employed to encrypt the content and also to compress the content.

30. The medium of claim 29 comprising:

a first module for compressing the content based at least in part on a content key to result in compressed content; and

a second module for encrypting the compressed content based at least in part on the content key to result in encrypted compressed content,

wherein the encrypted compressed content from the output of the encryption element cannot be decompress without the content key.

31. The medium of claim 29 wherein the first module compresses based on a number of adjustable parameters and wherein the first module employs the content key as at least one of the adjustable parameters.

32. The system of claim 31 wherein the first module compresses based on an internal representation having DCT coefficients of macroblocks, and wherein the first module scrambles and noises the coefficients according to the content key.

33. The system of claim 31 wherein the first module compresses based on a quantizer for performing a lossy quantization step, and wherein the first module dithers the quantizer according to the content key.