Volatile device keys and applications thereof

• US 20060210082A1
• Filed: 11/14/2005
• Published: 09/21/2006
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Verayo, Inc.
• Original Assignee: Verayo, Inc.
• Inventors: Devadas, Srinivas, Ziola, Thomas
• Granted Patent: US 7,564,345 B2
• Time in Patent Office: Days
• US Class Current: 380/277
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/445 by mutual authentication, e.g. between devices or programs
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/76 in application-specific integrated circuits [ASIC] or field-programmable devices, e.g. field-programmable gate arrays [FPGA] or programmable logic devices [PLD]
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• CPC Class Codes: G11C 16/20 Initialising; Data preset; Chip identification
• CPC Class Codes: G11C 16/22 Safety or protection circuits preventing unauthorised or accidental access to memory cells
• CPC Class Codes: G11C 2029/4402 Internal storage of test result, quality data, chip identification, repair information
• CPC Class Codes: G11C 2029/5002 Characteristic
• CPC Class Codes: G11C 7/24 Memory cell safety or protection circuits, e.g. arrangements for preventing inadvertent reading or writing; Status cells; Test cells
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/0838 Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these network architectures or network communication protocols for key exchange in a packet data network H04L63/061
• CPC Class Codes: H04L 9/0877 using additional device, e.g. trusted platform module [TPM], smartcard, USB or hardware security module [HSM]
• CPC Class Codes: H04L 9/304 based on error correction codes, e.g. McEliece
• CPC Class Codes: H04L 9/3278 using physically unclonable functions [PUF]

Abstract

A key is determined from a volatile response using circuitry on the device. The volatile response depend on process variation in fabrication of the device. Error control data that depends on the first volatile response can be computed, stored externally to the device, and then used to generate the key using a volatile response using the circuit. Applications of volatile keys include authentication and rights management for content and software.

Claims

1. A method for determining a key on a device:

generating a first volatile response using circuitry on the device, the volatile response depending on process variation in fabrication of the device;

computing first error control data that depends on the first volatile response;

storing the first error control data externally to the device;

generating a second volatile response using the circuitry on the device; and

generating the key using the externally stored first error control data and the second volatile response.

2. The method of claim 1 wherein the first error control data includes a syndrome computed from the first volatile response.

3. The method of claim 1 wherein generating the key using the first error control data and the second volatile response includes

providing the first error control data to the device,

correcting the second volatile response using the provided first error control data to yield the first volatile response, and

generating the key using the corrected second volatile response.

4. The method of claim 1 wherein generating the key using the first error control data and the second volatile response includes

computing second error control data that depends on the second volatile response,

providing the second error control data from the device,

combining the first error control data and the second error control data outside the device to produce correction data,

providing the correction data to the device,

correcting the second volatile response using the correction data to yield the first volatile response, and

generating the key using the corrected second volatile response.

5. A method for sharing a secret with a device comprising:

providing a public key to the device;

generating a volatile response in the device;

encrypting the volatile response using the public key;

receiving the encrypted volatile response from the device; and

decrypting the volatile response using a private key corresponding to the public key.

6. The method of claim 5 wherein generating the volatile response include generating the volatile response based on the public key.

7. The method of claim 5 further comprising providing a quantity to the device for combining with volatile response to generate the secret in the device.

8. The method of claim 7 wherein the quantity for combining with the volatile response is insufficient to determine the secret.

9. A method for key generation on a device comprising:

generating a private key and a corresponding public key on the device without permitting disclosure of the private key outside the device, the private key not being determinable from non-volatile quantities stored on the device;

disclosing the public key from the device;

generating a second volatile response using circuitry on the device, the volatile response depending on process variation in fabrication of the device; and

regenerating the private key on the device using the second volatile response.

10. The method of claim 9 wherein generating the private key includes determining the private key using a first volatile response using the circuitry on the device.

11. The method of claim 9 wherein generating the private key includes generating a random number on the device, determining the private key using the random number, and determining a quantity for combining with the second volatile response in regenerating the private key.

12. The method of claim 9 further comprising determining a quantity on the device for use in generating the private key from the second volatile response, and storing the quantity outside the device.

13. A method comprising:

generating a first volatile response on each of a plurality of device, the volatile responses depending on process variation in fabrication of the devices;

storing data outside the devices associating the devices with quantities that depend on the respective first volatile responses; and

authenticating one of the devices including generating a second volatile response on the device, and comparing a quantity that depends on the second volatile response with a quantity in the stored data.

14. The method of claim 13 wherein authenticating the device includes determining whether the stored quantity that depends on the first volatile response for the device matches the quantity that depends on the second volatile response for the device.

15. The method of claim 13 wherein the quantity that depends on the first volatile response includes a non-invertible function of the first volatile response.

16. The method of claim 15 wherein the non-invertible function includes a public key encryption of the first volatile response.

17. A method for authenticating a device comprising:

authenticating by a first entity a first device using a first authentication method;

while authenticated using the first authentication method, establishing a shared secret between the first entity and the device, the shared secret being volatile on the device; and

while no longer authenticating the first device using the first authentication method, authenticating the first device using a second authentication method including regenerating the shared secret based on a volatile response of circuitry on the device that depends on process variation in fabrication of the device based on the first device.

18. The method of claim 17 wherein establishing the shared secret includes receiving a quantity that depends on the volatile response from the first device at the first entity, and providing a quantity from first entity to the device for combining with the volatile response to regenerate the shared secret.

19. The method of claim 17 wherein authenticating by a first entity a first device using a first authentication method includes confirming connection of the first device to the first entity.

20. The method of claim 19 wherein confirming connection of the first device to the first entity includes connecting the first device to the first entity using a dedicated communication link.

21. A method for authenticating a device comprising:

authenticating the device by a first entity, including establishing a first secret shared between the first entity and the device, the first secret in the device being volatile; and

authenticating the device by a second entity, including using the first shared secret to establish a second shared secret shared between the second entity and the device.

22. The method of claim 21 wherein authenticating the device by the second entity includes withholding from the second entity information allowing the second entity to determine the first secret.

23. The method of claim 21 wherein authenticating the device by the second entity includes receiving a quantity dependent on the first secret from the first entity, and verifying that the device is the source of a message using the received quantity.

24. The method of claim 21 further verifying by the first entity using the first secret that the device is the source of a message to the second entity.

25. A device comprising:

a volatile key generator for generating a decryption key, the device being configured to prevent disclosure of the generated decryption key outside the device;

a decryption unit coupled to the key generator for accepting the decryption key;

an interface for accepting encrypted content at the device and providing the encrypted content to the decryption unit;

a converter for processing the decrypted content; and

an interface for providing the processed decrypted content from the device.

26. The device of claim 25 wherein the content includes at least one of audio content and video content.

27. The device of claim 25 wherein the converter includes a digital-to-analog converter, and the processed decrypted content includes an analog signal.

28. The device of claim 25 wherein the processed decrypted content is insufficient to recreate the decrypted content.

29. A device comprising:

an interface for coupling the device to a processing system;

a volatile key generator for generating a decryption key, the device being configured to prevent disclosure of the generated decryption key outside the device;

a decryption unit coupled to the key generator for accepting the decryption key to decrypt information, including encrypted instructions, received over the interface from the processing system; and

a processor coupled to the decryption unit for executing the instructions and providing a result of the executing of the instructions on the device to the processing system.

30. A method comprising:

distributing software for execution on a processing system;

distributing a device for coupling to the processing system;

executing the software on the processing system, including

passing encrypted instructions from the processing system to the device,

generating a volatile key on the device,

decrypting the instructions on the device,

passing a result that depends on the decrypted instructions from the device to the processing system;

permitting execution of a portion of the software on the processing system only if the passed result matches a predetermined result.

31. The method of claim 30 wherein the result comprises the decrypted instructions.

32. The method of claim 30 wherein the result comprises a result of executing the decrypted instruction on a processor on the device.

33. A proximity device comprising:

circuitry for generating a volatile response that varies among devices fabricated according to a common design;

programmable storage for data; and

a radio interface providing remote access to the stored data and to the volatile response.

34. The device of claim 33 wherein the device comprises a radio frequency identification device (RFID).

35. The device of claim 33 wherein the circuitry for generating the volatile response consists of fewer than 100 logic gates.

36. A method comprising:

storing information in a storage of a proximity device via a radio interface of the device;

accessing a volatile response of a circuit on the device, the volatile response varying among devices fabricated according to a common design; and

storing data associating the volatile response and the stored information outside the proximity device.

37. The method of claim 36 further comprising:

retrieving the stored information and a volatile response of the circuit via the radio interface; and

verifying retrieved stored information and volatile response match the stored data.

38. The method of claim 36 wherein accessing the volatile response includes providing an input value via the radio interface to the device and providing the input value to the circuit for generating the volatile response.

39. The method of claim 38 further comprising subsequently providing the input value to the device and retrieving the stored information and a volatile response of the circuit generated using the input value.