Interpreter using cryptographic values of a playback device's keys to authorize the playback device

1. A non-transitory computer-readable medium comprising:

encrypted digital content, the encrypted digital content including representations of a plurality of versions of a plurality of regions of the encrypted digital content, each version of the plurality of versions being encrypted with a unique cryptographic key; and

program logic for processing by an interpreter in a playback device, including:

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 a plurality of cryptographic keys, each cryptographic key of the plurality of cryptographic kegs corresponding to a unique version of the plurality of versions, the plurality of cryptographic keys not being accessible by said program logic;

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

program logic configured to derive values of the plurality of cryptographic keys for decrypting a particular version of the plurality of versions and thereby enable playback of the particular version, if it is it determined that playback is authorized.

2. The non-transitory computer-readable medium of claim 1 where said program logic is further configured to:

not derive values of the plurality of cryptographic keys if playback is not authorized.

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

obtain from said playback device information identifying said playback device;

and 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 non-transitory computer-readable medium of claim 1 further comprising:

information identifying the manufacturer of said medium, at least one characteristic identifiable by said player identifying that said medium is not consumer-recordable.

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

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

an input interface usable to input said encrypted digital content and associated program logic, the encrypted digital content including representations of a plurality of versions of a plurality of regions of the encrypted digital content, each version of the plurality of versions being encrypted with a unique cryptographic key;

a memory usable to store inputs read from said interface;

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

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

a cryptographic module:

having access to a plurality of cryptographic keys, each cryptographic key of the plurality of cryptographic keys corresponding to a unique version of the plurality of versions; and

configured to perform cryptographic processing using the plurality of cryptographic keys as directed by said program logic, such that said program logic can obtain the results of said cryptographic processing but cannot determine values of the plurality of cryptographic keys; and

an output interface for outputting after decryption, a particular version of the plurality of versions by using the results of the cryptographic processing.

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 coupled to a removable module comprising:

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

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:

said playback device;

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

at least one device coupled 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 :

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

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 the particular version by 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 particular version such that a third party can determine said information by analyzing a recording of said decrypted particular version outputted from said output interface.

14. The device of claim 13 where:

said device is capable of embedding said information by using said information to select the particular version to output from among said plurality of versions; and

said decryption circuit includes logic to synchronize decryption key changes.

15. The device of claim 6 further comprising:

an internal nonvolatile memory:

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

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

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 content, the method comprising:

reading data from a medium, where said data incorporates processing instructions combined with encrypted digital content, the encrypted digital content including representations of a plurality of versions of a plurality of regions of the encrypted digital content, each version of the plurality of versions being encrypted with a unique cryptographic key;

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

using cryptographic keys of a plurality of cryptographic keys in a cryptographic operation to produce a result, each cryptographic key of the plurality of cryptographic keys corresponding to a unique version of the plurality of versions, the plurality of cryptographic keys being accessible to said player device,

returning the result to said processing instructions;

using the result to decrypt said encrypted digital content; and

outputting a representation of said decrypted digital content by using an output interface.

18. The method of claim 17 further comprising:

identifying a device coupled to said output interface;

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

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 coupled device; and

outputting said decrypted digital content at said specified output quality.

19. The method of claim 17 further comprising:

updating a protected nonvolatile memory to indicate that said digital content was played; and

securely reporting 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 including transmitting at least one message via said output interface to a user of said player device.

22. The method of claim 17 further comprising:

analyzing information including a type of said player device; and

based on said analysis, enabling playback of additional bonus digital content 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 content.

24. The method of claim 17 further comprising:

transmitting a value to an output device coupled to said output interface; and

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