Protection Scheme for AACS Keys

• US 20100020968A1
• Filed: 01/04/2008
• Published: 01/28/2010
• Est. Priority Date: 01/04/2008
• Status: Active Grant

• Current Assignee: ArcSoft, Inc.
• Original Assignee: ArcSoft, Inc.
• Inventors: Jin, Chao, Sun, Weitao
• Granted Patent: US 9,137,015 B2
• Time in Patent Office: Days
• US Class Current: 380/200
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/2585 Generation of a revocation list, e.g. of client devices involved in piracy acts
• CPC Class Codes: H04N 21/8355 involving usage data, e.g. number of copies or viewings allowed
• CPC Class Codes: H04N 5/765 Interface circuits between an apparatus for recording and another apparatus
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

A method for protecting a software video player having Advanced Access Content System (AACS) includes reading segments of an encrypted first key from noncontiguous regions of memory, assembling the segments to form the encrypted first key, decrypting the encrypted first key with a second key to form a first key, extracting AACS key data from a pack file, decrypting the AACS key data to retrieve AACS Device Keys, generating an AACS Title Key using the AACS Device Key, clearing the AACS Device Keys and the first key from memory after the AACS Title Key is generated, decrying encrypted AACS content with the AACS Title Key to form AACS content, and displaying the AACS content.

Claims

1. A method for protecting a software video player having Advanced Access Content System (AACS), comprising:

creating a temporary random key when the software video player is started;

encrypting a fixed random key with the temporary random key to form an encrypted fixed random key;

dividing the encrypted fixed random key into the segments;

storing the segments at noncontiguous regions of memory;

reading the segments from the noncontiguous regions of memory;

assembling the segments to form the encrypted fixed random key;

decrypting the encrypted fixed random key with the temporary random key to form the fixed random key;

extracting AACS key data from a pack file;

decrypting the AACS key data with the fixed random key to retrieve AACS Device Keys;

generating an AACS Title Key using the AACS Device Key;

clearing the AACS Device Keys and the fixed random key from memory after the AACS Title Key is generated;

decrying encrypted AACS content with the AACS Title Key to form AACS content; and

displaying the AACS content.

2. The method of claim 1, wherein said reading, said assembling, said decrypting the encrypted first key, said extracting, said decrypting the AACS key data, said generating, said clearing, and said decrypting AACS content occur dynamically only when the AACS content must be displayed.

3. The method of claim 1, wherein said decrypting the AACS key data further comprising retrieving AACS Host Key, the method further comprising:

authenticating an optical disk drive using the AACS Host Key; and

reading the encrypted AACS content from the optical disk drive.

4. The method of claim 1, further comprising:

generating a random number at a first module of the software video player;

transmitting the random number from a first module to a second module of the software video player;

encrypting the random number with a third key at the second module to form an encrypted random number;

transmitting the encrypted random number from the second module to the first module;

decrypting the encrypted random number with the third key at the first module; and

verifying the random number at the first module, wherein the second module is authenticated with the first module when the random number has not changed.

5. The method of claim 4, wherein the first and the second modules are selected from the group consisting of a BDMV engine, a codec engine, and an application layer.

6. The method of claim 5, wherein said displaying the AACS content comprising transmitting the AACS content from the BDMV engine to the codec engine, the codec engine converting the AACS content into a video.

7. The method of claim 4, further comprising:

creating a random key at the first module;

transmitting the random number key from the first module to the second module;

encrypting AACS content with the random key at the first module;

transmitting the encrypted AACS content from the fist module to the second module; and

decrypting the encrypted AACS content with the random key at the second module.

8. The method of claim 1, further comprising:

terminating the software video player after detecting a debugger; and

terminating the software video player after detecting the software video player is under a debugging condition.

9. The method of claim 8, wherein said detecting a debugger comprises checking a thread information block (TIB) for flags that identify a running thread of a debugging tool.

10. The method of claim 8, wherein said detecting a debugger comprises creating object handles with driver, file, and server names of the debugger, wherein the debugger is detected when said creating fails.

11. The method of claim 8, wherein said detecting the software video player is under a debugging condition comprises determining if a parent process of the software video player is Windows Explorer, the software video player being under the debugging condition when the parent process is not Window Explorer.

12. The method of claim 1, further comprising executing junk codes to obfuscate other steps being performed by software video player.