Content security layer providing long-term renewable security

• US 20080049935A1
• Filed: 10/26/2007
• Published: 02/28/2008
• Est. Priority Date: 03/28/2001
• Status: Active Grant

• Current Assignee: Irdeto USA Incorporated (MultiChoice Group Ltd.)
• Original Assignee: Cryptography Research, Inc. (Rambus Inc.)
• Inventors: Carter, Matthew, Jun, Benjamin, Pearson, Peter, Kocher, Paul, Jaffe, Joshua
• Granted Patent: US 7,756,272 B2
• Time in Patent Office: Days
• US Class Current: 380/201
• 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 20/00166 involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00173 wherein the origin of the content is checked, e.g. determining whether the content has originally been retrieved from a legal disc copy or another trusted source
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00246 wherein the key is obtained from a local device, e.g. device key initially stored by the player or by the recorder
• CPC Class Codes: G11B 20/00659 involving a control step which is implemented as an executable file stored on the record carrier
• CPC Class Codes: G11B 20/00818 wherein the usage restriction limits the signal quality, e.g. by low-pass filtering of audio signals or by reducing the resolution of video signals
• CPC Class Codes: G11B 20/0084 wherein the usage restriction can be expressed as a specific time or date
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 2005/91342 the copy protection signal being an authentication signal
• 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 21/4135 external recorder interface circuits between an apparatus for recording television signals and a television receiver H04N5/775
• CPC Class Codes: H04N 21/4181 for conditional access
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/44236 : Monitoring of piracy processes or activities protecting computer platforms against harmful, malicious or unexpected behaviour or activities using intrusion detection and counter measures G06F21/566; computer virus detection and handling G06F21/56
• CPC Class Codes: H04N 21/4627 : Rights management associated to the content security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/8355 : involving usage data, e.g. number of copies or viewings allowed
• CPC Class Codes: H04N 21/8358 : involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection

Abstract

In an exemplary embodiment, digital content is mastered as a combination of encrypted data and data processing operations that enable use in approved playback environments. Player devices having a processing environment compatible with the content'"'"'s data processing operations are able to decrypt and play the content. Players can also provide content with basic functions, such as loading data from media, performing network communications, determining playback environment configuration, controlling decryption/playback, and/or performing cryptographic operations using the player'"'"'s keys. These functions allow the content to implement and enforce its own security policies. If pirates compromise individual players or content titles, new content can be mastered with new security features that block the old attacks. A selective decryption capability can also be provided, enabling on-the-fly watermark insertion so that attacks can be traced back to a particular player. Features to enable migration from legacy formats are also provided.

Claims

1. A computer-readable medium comprising:

(a) encrypted digital video; and

(b) program logic for processing by an interpreter in a playback device, including;

(i) program logic configured to query said playback device to obtain the results of cryptographic computations performed by said playback device, where said cryptographic operations use one or more cryptographic key values unique to said player and not accessible by said program logic;

(ii) program logic configured to determine whether playback is authorized to proceed on said playback device by using said obtained results;

(iii) program logic configured to derive at least one video decryption key to enable playback of said video, if it is it determined that playback is authorized.

2. The computer-readable medium of claim 1 where said program logic in (iii) is further configured to:

(A) derive said video decryption keys on authorized players, by using said cryptographic computation results; and

(B) not derive said video decryption cryptographic keys on unauthorized players.

3. The computer-readable medium of claim 1 further comprising program logic configured to:

(a) obtain from said playback device information identifying said playback device; and

(b) use said identifying information to modify the playback of said video so that a third party with knowledge of how said modification is performed can identify said playback device from a copy of the playback output.

4. The computer-readable medium of claim 1 further comprising:

(a) information identifying the manufacturer of said medium,

(b) at least one characteristic identifiable by said player identifying that said medium is not consumer-recordable.

5. The computer-readable medium of claim 1 further comprising a serial number uniquely identifying said medium.

6. A device for playing encrypted digital content, comprising:

(a) an input interface usable to input said encrypted digital content and associated program logic;

(b) a memory usable to store inputs read from said interface;

(c) a processor usable to read data from said interface and to store data in said memory;

(d) an interpreter, implemented using software executable on said processor and configured to interpret program logic read from said interface and stored in said memory;

(e) a cryptographic module;

(i) having access to at least one cryptographic key; and

(ii) configured to perform cryptographic processing using said cryptographic key as directed by said program logic, such that said program logic can obtain the results of said cryptographic processing but cannot determine the value of said at least one key; and

(e) an output interface for outputting said digital content.

7. The device of claim 6, where said input interface is a network interface capable of receiving a transmission over the Internet.

8. The device of claim 6 where said input interface is connected to a removable module comprising:

(i) a memory containing said encrypted digital content and associated program logic; and

(ii) cryptographic computation logic usable by said program logic and necessary to decrypt said content.

9. The device of claim 6 where said interpreter is configured to provide said program logic with access to information describing:

(i) said playback device;

(ii) at least one action requested by a user of said playback device; and

(iii) at least one device connected to said output interface.

10. The device of claim 6 where said cryptographic subunit comprises a removable, tamper-resistant hardware module.

11. The device of claim 6:

(i) where said encrypted digital content includes encrypted digital video distributed on an optically-readable medium; and

(ii) further configured to output said digital content in a form re-encrypted to deter unauthorized access to said output.

12. The device of claim 6, further comprising a decryption circuit configured to decrypt said content using cryptographic keys derived by said program logic.

13. The device of claim 12, where said decryption circuit is configured to embed information received from said interpreter in the decrypted content such that third party can determine said information by analyzing a recording of said content outputted from said output interface.

14. The device of claim 13 where:

(i) representations of a plurality of versions of a plurality of regions of said content are stored on a digital medium accessible by said input interface;

(ii) each of said versions is encrypted with a unique cryptographic key;

(iii) said device is capable of embedding said information by using said information to select portions of said content to output from among said plurality of versions; and

(iv) said decryption circuit includes logic to synchronize decryption key changes.

15. The device of claim 6 further comprising:

(a) an internal nonvolatile memory;

(i) containing security-related data accessible by said program logic operating on said interpreter; and

(ii) usable by said program logic to verify the security of said playback device; and

(b) cryptographic authentication logic to validate the authenticity of updates to said security-related data.

16. The device of claim 6 further comprising a visual indicator notifying a user of said playback device whether the quality of said digital content provided on said output interface has been reduced.

17. A method for playing encrypted digital video, comprising the steps of:

(a) reading data from a medium, where said data incorporates processing instructions combined with encrypted video data;

(b) using an interpreter within a player device, performing said processing instructions;

(c) using a secret key accessible to said player device, cryptographically transforming said data received with said processing instructions,

(d) returning the result of (c) to said processing instructions;

(e) using the result of said processing instructions to decrypt said encrypted video data; and

(f) outputting a representation of said decrypted video using an output interface.

18. The method of claim 17 further comprising:

(a) identifying a device connected to said output interface;

(b) determining that the security of said connected device is insufficient for high-quality playback, as a result of executing said processing instructions;

(c) said processing instructions specifying an output quality that is lower than the best quality represented on said medium, supported by said output interface, and supported by said connected device; and

(d) outputting said decrypted video at said specified output quality.

19. The method of claim 17 further comprising:

(a) updating a protected nonvolatile memory to indicate that said digital video was played; and

(b) securely reporting a result of said nonvolatile memory update to a third party to enable billing for playback.

20. The method of claim 19 further comprising using a public key to verify a digital signature on at least a portion of said processing instructions prior to allowing access to said nonvolatile memory.

21. The method of claim 17 where (b) includes transmitting at least one message via said output interface to a user of said player device.

22. The method of claim 17 further comprising:

(a) analyzing information including the type of said player; and

(b) based on said analysis, enabling playback of additional bonus video stored on said media.

23. The method of claim 17 further comprising using a codec implemented in said processing instructions operating on said interpreter to decompress said digital video.

24. The method of claim 17 further comprising:

(a) transmitting a value to an output device connected to said output interface; and

(b) receiving a cryptographically-transformed representation of said value from said output device.

25. A device for playing encrypted digital content, comprising:

(a) means for inputting said encrypted digital content and associated program logic from a removable digital medium;

(b) means for storing program logic read from said interface;

(c) means for interpreting said program logic;

(d) means for performing cryptographic processing using a secret key as directed by said program logic, whereby said program logic can obtain the results of said cryptographic processing, but cannot determine the value of said secret key; and

(e) means for outputting said digital content.