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

• US 7,239,708 B2
• Filed: 06/27/2001
• Issued: 07/03/2007
• Est. Priority Date: 06/27/2001
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: England, Paul, Peinado, Marcus, Sankaranarayan, Mukund
• Primary Examiner(s): Zand; Kambiz
• Assistant Examiner(s): Nalven; Andrew L.
• Application Number:
  US09/892,367
• Publication Number:
  US 20020006204A1
• Time in Patent Office: 2,197 Days
• Field of Search: 380/44, 380/269, 280/28, 713/200, 705/51
• 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 developing a content key and for decrypting the content based at least in part on the developed content key; and

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

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

wherein the decompression element has a plurality of adjustable parameters and wherein the decompression element employs the content key as at least one of the adjustable parameters,

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,

wherein the decompression element includes an internal representation that includes DCT coefficients of macroblocks, and wherein such coefficients are de-scrambled and de-noised according to the content key, and

wherein the decryption element and the decompression element are closely physically related to one another so as to protect the content key as supplied by the decryption element to the decompression element, such close physical relationship comprising one of the decompression element residing in a process address space of the decryption element on the computer system and the decryption element residing in a process address space of the decompression element on the computer system.

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

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

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

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

wherein the compression element has a plurality of adjustable parameters and wherein the compression element employs the content key as at least one of the adjustable parameters,

wherein the compression element includes a quantizer for performing a lossy quantization step, and wherein the quantizer is dithered according to the content key,

wherein the compression element includes an internal representation that includes DCT coefficients of macroblocks, and wherein such coefficients are scrambled and noised according to the content key, and

wherein the encryption element and the compression element are closely physically related to one another so as to protect the content key as supplied by the encryption element to the compression element, such close physical relationship comprising one of the compression element residing in a process address space of the encryption element on the computer system and the encryption element residing in a process address space of the compression element on the computer system.

4. The computer system of claim 3 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 decompressed without the content key.

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

developing a content key in a decryption element;

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

decompressing the content in a decompression element based at least in part on the content key, the decryption element supplying the content key to the decompression element,

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

wherein decompression is based on a plurality of adjustable parameters and wherein decompression comprises employing the content key as at least one of the adjustable parameters,

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,

wherein decompression is also based on an internal representation that includes DCT coefficients of macroblocks, and wherein such decompression comprises de-scrambling and de-noising such coefficients according to the content key, and

wherein the decryption element and the decompression element are closely physically related to one another so as to protect the content key as supplied by the decryption element to the decompression element, such close physical relationship comprising one of the decompression element residing in a process address space of the decryption element on the computer system and the decryption element residing in a process address space of the decompression element on the computer system.

6. The method of claim 5 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.

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

developing a content key in an encryption element;

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

compressing the content in a compression element based at least in part on the content key, the encryption element supplying the content key to the compression element,

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

wherein compression is based on a plurality of adjustable parameters and wherein compression comprises employing the content key as at least one of the adjustable parameters,

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,

wherein compression is also based on an internal representation that includes DCT coefficients of macroblocks, and wherein such compression comprises scrambling and-noising such coefficients according to the content key, and

wherein the encryption element and the compression element are closely physically related to one another so as to protect the content key as supplied by the encryption element to the compression element, such close physical relationship comprising one of the compression element residing in a process address space of the encryption element on the computer system and the encryption element residing in a process address space of the compression element on the computer system.

8. The method of claim 7 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.

9. 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 developing a content key and for decrypting the content based at least in part on the developed content key; and

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

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

wherein the second module decompresses based on a plurality of adjustable parameters and wherein the second module employs the content key as at least one of the adjustable parameters,

wherein the second module decompresses based on a quantizer for performing a lossy quantization step, and wherein the second module de-dithers the quantizer according to the content key,

wherein the second module decompresses based on an internal representation that includes DCT coefficients of macroblocks, and wherein such second module de-scrambles and de-noises such coefficients according to the content key, and

wherein the first module and the second module are closely physically related to one another so as to protect the content key as supplied by the first module to the second module, such close physical relationship comprising one of the second module as instantiated on a computer system residing in a process address space of the first module as instantiated on the computer system and the first module as instantiated on the computer system residing in a process address space of the second module on the computer system.

10. The medium of claim 9 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.

11. 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 developing a content key and for encrypting the content based at least in part on the developed content key; and

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

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

wherein the first module compresses based on a plurality of adjustable parameters and wherein the first module employs the content key as at least one of the adjustable parameters,

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

wherein the first module compresses based on an internal representation that includes DCT coefficients of macroblocks, and wherein such first module scrambles and noises such coefficients according to the content key, and

wherein the first module and the second module are closely physically related to one another so as to protect the content key as supplied by the first module to the second module, such close physical relationship comprising one of the second module as instantiated on a computer system residing in a process address space of the first module as instantiated on the computer system and the first module as instantiated on the computer system residing in a process address space of the second module on the computer system.

12. The medium of claim 11 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.