Self-protecting digital content

• US 20080101604A1
• Filed: 10/31/2007
• Published: 05/01/2008
• 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: Lawson, Nathaniel, Laren, Carter, Jun, Benjamin, Kocher, Paul, Jaffe, Joshua, Pearson, Peter
• Granted Patent: US 7,984,511 B2
• Time in Patent Office: Days
• US Class Current: 380/210
• CPC Class Codes: G06F 21/50 Monitoring users, programs or devices to maintain the integrity of platforms, e.g. of processors, firmware or operating systems
• CPC Class Codes: G06F 21/62 Protecting access to data via a platform, e.g. using keys or access control rules
• CPC Class Codes: G06F 21/6281 at program execution time, where the protection is within the operating system
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00
• 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 20/00115 wherein the record carrier stores a unique medium identifier
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00231 wherein the key is obtained from a local external medium, e.g. a card
• 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 20/00253 wherein the key is stored on the record carrier
• CPC Class Codes: G11B 20/00449 content scrambling system [CSS]
• 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 20/00884 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 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 2209/606 Traitor tracing
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3249 using RSA or related signature schemes, e.g. Rabin scheme
• CPC Class Codes: H04N 2005/91342 the copy protection signal being an authentication signal
• CPC Class Codes: H04N 21/25816 : involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• 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 21/42646 : for reading from or writing on a non-volatile solid state storage medium, e.g. DVD, CD-ROM
• 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 21/8358 : 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 7/1675 : Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

Technologies are disclosed to transfer responsibility and control over security from player makers to content authors by enabling integration of security logic and content. An exemplary optical disc carries an encrypted digital video title combined with data processing operations that implement the title'"'"'s security policies and decryption processes. Player devices include a processing environment (e.g., a real-time virtual machine), which plays content by interpreting its processing operations. Players also provide procedure calls to enable content code to load data from media, perform network communications, determine playback environment configurations, access secure nonvolatile storage, submit data to CODECs for output, and/or perform cryptographic operations. Content can insert forensic watermarks in decoded output for tracing pirate copies. If pirates compromise a player or title, future content can be mastered with security features that, for example, block the attack, revoke pirated media, or use native code to correct player vulnerabilities.

Claims

1. A method of distributing audiovisual content in a form playable by a plurality of models of player devices in conjunction with program code, comprising:

(a) obtaining said content in digital, scrambled form;

(b) associating said program code with said content, where said program code is adapted to;

(i) be executable by interpreters implemented in a plurality of models of player devices;

(ii) include a plurality of countermeasure routines, each said routine for mitigating a security weakness affecting at least one of said plurality of models of player devices, said plurality of countermeasure routines collectively mitigating security weaknesses in multiple models of player devices; and

(iii) cryptographically authenticate the model of a particular player device seeking to play said audiovisual content,

(iv) perform operations necessary for the unscrambling of said audiovisual content on said particular player device in (iii) provided that;

(A) said program code has cryptographically authenticated said particular player device; and

(B) when said particular player device is authenticated as being of a model for which a countermeasure is required, at least one of said countermeasure routines is executed to provide a result which is necessary for said unscrambling of said audiovisual content on said particular player device; and

(c) distributing said content in conjunction with said associated program code.

2. The method of claim 1 where said audiovisual content is compressed, and step (c) includes transmitting both compressed audiovisual content and said associated program code, over a network to a remote device configured to execute said program code and decompress compressed audiovisual content.

3. The method of claim 2 where said remote device configured to execute said program code is a server configured to execute said program code as part of a transaction over said network, where said transaction includes:

(i) processing payment information; and

(ii) responsively transmitting said audiovisual content in conjunction with said code to said particular player device.

4. The method of claim 1 where:

(i) said program code is adapted to apply different sets of said operations on different player devices; and

(ii) said operations are adapted to identify player devices used in the production of unauthorized copies of said audiovisual content.

5. The method of claim 1 where step (c) includes distributing said content and associated program code together via an optical disc.

6. The method of claim 1 where said program code is further adapted to:

(i) retrieve information stored in a nonvolatile memory of a player device;

(ii) use said retrieved information to determine whether playback of said audiovisual content is authorized; and

(iii) perform said operations only if said playback is determined to be authorized.

7. The method of claim 1 where said program code is adapted to cryptographically authenticate a player device by:

(i) submitting a challenge value to said player device;

(ii) receiving from said player device a digital signature and a digital certificate; and

(iii) validating that said digital signature corresponds to said challenge value and that said digital certificate authenticates a key used to produce said digital signature.

8. The method of claim 1 where:

(i) said program code cryptographically authenticates a player device by submitting at least one ciphertext value to said player device, and receiving from said player device at least one result whose derivation includes decrypting said ciphertext;

(ii) when executing on player devices unaffected by said weaknesses, said program code uses said decryption result to enable said operations without using said countermeasure routines; and

(iii) when executing on player devices affected by said weaknesses, said transformations require a result from at least one of said countermeasure routines.

9. A machine-readable media in a form playable by a plurality of models of player devices, said machine-readable media comprising:

(a) audiovisual content in digital, scrambled form; and

(b) program code adapted to;

(i) execute in interpreters implemented in a plurality of models of player devices seeking to decode said audiovisual content;

(ii) include a plurality of countermeasure routines, each said routine for mitigating a security weakness affecting at least one of said plurality of models of player devices, said plurality of countermeasure routines collectively mitigating security weaknesses in multiple models of player devices;

(iii) authenticate the model of a particular player device seeking to decode said audiovisual content;

(iv) perform operations necessary for the unscrambling of said audiovisual content on said particular player device provided that;

(A) said program code has authenticated that said particular player device is a valid model; and

(B) when said particular player device is authenticated as being of a model for which a countermeasure is required, at least one of said countermeasure routines is executed to provide a result which is necessary for said unscrambling of said audiovisual content on said particular player device.

10. The apparatus of claim 9 where said program code is adapted to enable unscrambling provided that said program code has verified that said player device possesses valid cryptographic keys.

11. The apparatus of claim 9 where each said countermeasure routine is adapted to mitigate a different security weakness.

12. The apparatus of claim 9 where said program code decrypts said countermeasure routine using a cryptographic key associated with said playback device.

13. An apparatus comprising program code stored on machine-readable media containing encrypted audiovisual content for playback on any of a plurality of playback device models, said program code adapted for execution by an audiovisual content player device, said program code adapted to when executed to:

(a) identify at least one characteristic of the player device;

(b) determine whether a security weakness characterizes said playback device based on the identified characteristic;

(c) if the security weakness characterizes the device;

(i) select a countermeasure routine corresponding to the weakness;

(ii) mitigate the weakness by causing said playback device to execute the selected countermeasure routine; and

(iii) decode audiovisual content using a result produced by the successful operation of the selected countermeasure routine; and

(d) if the weakness does not characterize the device, decode audiovisual content using at least one cryptographic key contained in said playback device.

14. The apparatus of claim 13 where said machine readable media includes optical media.

15. The apparatus of claim 13 where:

(a) said program code is configured to execute in an interpreter common to a plurality of device architectures; and

(b) at least a portion of the selected countermeasure routine is configured to be executed directly as native code on a microprocessor contained in the player device.

16. The apparatus of claim 15 further comprising a digital signature for authenticating said native code.

17. A method for enabling a playback device containing a nonvolatile memory to determine whether a digital medium has been revoked, comprising:

(a) reading a media identifier from an optical disc;

(b) verifying that said media identifier is not represented in a revocation list stored in said player device'"'"'s nonvolatile memory;

(c) storing said media identifier in a playback history contained in said player device'"'"'s nonvolatile memory;

(d) reading a list of revoked media identifiers from said optical disc;

(e) identifying any media identifier that is represented in said playback history and that is also represented on said revocation list;

(f) adding any such identified media identifier to said revocation list contained in the player'"'"'s nonvolatile memory.

18. The method of claim 17 further comprising preventing playback of encrypted audiovisual content contained on said optical disc if as a result of step (b) it is determined that said media identifier is represented in said revocation list.

19. The method of claim 17 further comprising performing playback of encrypted audiovisual content contained on said optical disc at reduced quality if as a result of step (b) it is determined that said media identifier is represented in said revocation list.

20. The method of claim 17 further comprising authenticating said media identifier using a digital signature read from said optical disc.

21. An apparatus comprising instructions stored on machine-readable media, said instructions adapted for execution by a device that controls playback of audiovisual content stored on an optical disc and that has nonvolatile memory, said instructions when executed causing said device to:

(a) read a media identifier from said optical disc;

(b) store said media identifier in a playback history contained in said nonvolatile memory;

(d) read said playback history from said nonvolatile memory;

(e) identify any media identifier that is represented in said playback history and is also represented in a revocation list stored in said nonvolatile memory;

(f) add any identified media identifier to said revocation list contained in said nonvolatile memory.

22. The apparatus of claim 21 where both said instructions and said audiovisual content are stored together on said optical disc.

23. The apparatus of claim 22 where said instructions are further adapted to as part of reading a media identifier from an optical disc, verify that said media identifier is not represented in said revocation list stored in said device'"'"'s nonvolatile memory.