Tamper Resistant Circuitry and Portable Electronic Devices

• US 20070266447A1
• Filed: 03/27/2007
• Published: 11/15/2007
• Est. Priority Date: 03/28/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hollander, James F.
• Granted Patent: US 8,050,657 B2
• Time in Patent Office: Days
• US Class Current: 726/34
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06F 21/81 by operating on the power supply, e.g. enabling or disabling power-on, sleep or resume operations

Abstract

A portable electronic device. Tamper-resistant circuitry for inclusion in an electronic device. The tamper-resistant circuitry comprises wireless receiving circuitry operable to receive an incoming communication. The tamper-resistant circuitry also comprises a first circuit operable to change a signal state in response to the incoming communication. The tamper-resistant circuitry also comprises a verification sensor circuit coupled to the first circuit. The sensor is operable to detect a circuit condition indicative of unauthorized use and upon detection of the circuit condition to prevent the change of the signal state.

Claims

1. Tamper-resistant circuitry for inclusion in an electronic device, the tamper-resistant circuitry comprising:

wireless receiving circuitry operable to receive an incoming communication;

a first circuit operable to change a signal state in response to the incoming communication; and

a verification sensor circuit coupled to the first circuit and operable to detect a circuit condition indicative of unauthorized use and upon detection of the circuit condition to prevent the change of the signal state.

2. The tamper-resistant circuitry of claim 1 wherein the verification sensor circuit is operable to detect the circuit condition indicative of unauthorized use in response to loading a node in the first circuit with different impedances and measuring a respective resultant parameter associated with the node and for each of the different impedances.

3. The tamper-resistant circuitry of claim 2 wherein the resultant parameter comprises a change in voltage measured relative to the node.

4. The tamper-resistant circuitry of claim 2 wherein the resultant parameter comprises a time to accumulate a charge relative to the node.

5. The tamper-resistant circuitry of claim 1 wherein the verification sensor circuit is operable to detect the circuit condition indicative of unauthorized use in response to driving a node in the first circuit with different frequencies and measuring a respective resultant parameter associated with the node and for each of the different frequencies.

6. The tamper-resistant circuitry of claim 5 wherein the different frequencies comprise direct current zero frequency and at least one alternating current frequency.

7. The tamper-resistant circuitry of claim 5:

wherein the electronic device comprises a processor; and

wherein at least one of the different frequencies is generated by a clock oscillator for providing a clock signal to the processor.

8. The tamper-resistant circuitry of claim 1 wherein the verification sensor circuit comprises:

circuitry for measuring a first parameter associated with at least one node of the first circuit; and

circuitry for comparing the first parameter to a range of acceptable values, wherein the verification sensor is operable to detect the circuit condition indicative of unauthorized use in response to a determination from the comparing that the first parameter is outside the range of acceptable values.

9. The tamper-resistant circuitry of claim 8:

wherein the circuitry for measuring is for measuring a plurality of parameters associated with the at least one node of the first circuit, wherein the first parameter is one of the plurality of parameters; and

wherein the circuitry for comparing the parameter to a range of acceptable values is for comparing each parameter in the plurality of parameters to a respective range of acceptable values, wherein the verification sensor is operable to detect the circuit condition indicative of unauthorized use in response to a determination from the comparing that any parameter in the plurality of parameters is outside the respective range of acceptable values.

10. The tamper-resistant circuitry of claim 9 wherein each respective range of acceptable values corresponds to a different frequency applied to the at least one node.

11. The tamper-resistant circuitry of claim 10 wherein at least one different frequency comprises a direct current zero frequency and at least one different frequency comprises an alternating current frequency.

12. The tamper-resistant circuitry of claim 10:

wherein the electronic device comprises a processor; and

wherein at least one different frequency is generated by a clock oscillator for providing a clock signal to the processor.

13. The tamper-resistant circuitry of claim 8 wherein the circuitry for measuring is operable to load the at least one node at different frequencies.

14. The tamper-resistant circuitry of claim 8 and further comprising circuitry for storing a respective maximum level and a respective minimum level to define at least one such range of acceptable values.

15. The tamper-resistant circuitry of claim 14 and further comprising circuitry for providing a data indication of integrity verification for each respective range of acceptable values.

16. The tamper-resistant circuitry of claim 14 and further comprising circuitry for adjusting at least one of the respective maximum level and respective minimum level in response to a variable affecting the first parameter.

17. The tamper-resistant circuitry of claim 16:

wherein the electronic device is operable in response to a battery; and

wherein the variable affecting the first parameter comprises a level of charge in the battery.

18. The tamper-resistant circuitry of claim 16 wherein the circuitry for adjusting comprises adjustment circuitry operable to apply a correction selected from a set consisting of linear, quadratic, cubic, higher-order, and multi-variate.

19. The tamper-resistant circuitry of claim 17 wherein the circuitry for adjusting comprises circuitry operable to access a lookup table.

20. The tamper-resistant circuitry of claim 16 wherein the variable comprises temperature.

21. The tamper-resistant circuitry of claim 1 wherein the electronic device is selected from a set consisting of a cellular telephone, a personal digital assistant, a content player, a pager, a video game player, an email communication device, and an alarm clock.

22. The tamper-resistant circuitry of claim 1 further comprising a second circuit selected from the group consisting of a ringer, a vibrator, a display, a light, a motor, a driver, an amplifier, an LED, an interface, a DTMF input, a DTMF output, and a headphone/earphone;

and wherein the change of the signal state is for causing operation of the second circuit.

23. The tamper-resistant circuitry of claim 1 wherein the change of the signal state comprises asserting a de-asserted signal.

24. The tamper-resistant circuitry of claim 1 wherein the change of the signal state comprises de-asserting an asserted signal.

25. The tamper-resistant circuitry of claim 24 wherein de-asserting an asserted signal comprises de-asserting a voltage signal.

26. The tamper-resistant circuitry of claim 1 wherein the incoming communication comprises data selected from a set consisting of voice data, video data, text data, and control data.

27. The tamper-resistant circuitry of claim 1 wherein the verification sensor circuit is operable to detect the circuit condition at different times.

28. The tamper-resistant circuitry of claim 27 wherein the different times are selected from a set consisting of start-up of the electronic device, reset of the electronic device, randomized times, fixed-period times, and in response to a requested operation of a circuit that requires the change of the signal state.

29. The tamper-resistant circuitry of claim 1 wherein the verification sensor circuit comprises a processor.

30. The tamper-resistant circuitry of claim 2 wherein the resultant parameter is selected from a set consisting of a voltage, current, impedance, a change in voltage, a change in current, and a change in impedance.

31. The tamper-resistant circuitry of claim 1 and wherein:

the first circuit includes a plurality of circuits each circuit in the plurality of circuits operable to change a respective signal state in response to the incoming communication; and

the verification sensor circuit includes a plurality of verification sensors coupled to the first circuit, wherein each verification sensor in the plurality of verification sensors is operable to detect a circuit condition indicative of unauthorized use.

32. Tamper-resistant circuitry for inclusion in an electronic device, the tamper-resistant circuitry comprising:

a first circuit operable to change a signal state in response to an event; and

a verification sensor circuit coupled to the first circuit, the verification sensor circuit having a configurable parameter range and operable to detect a circuit condition outside the configurable parameter range and upon detection of the circuit condition outside the configurable parameter range to prevent the change of the signal state.

33. The tamper-resistant circuitry of claim 32:

wherein the verification sensor circuit comprises;

circuitry for measuring a first parameter associated with at least one node of the first circuit;

circuitry for comparing the first parameter to the configurable parameter range, wherein the verification sensor is operable to detect the circuit condition in response to a determination from the comparing that the first parameter is outside the configurable parameter range.

34. The tamper-resistant circuitry of claim 33:

wherein the circuitry for measuring is operable for measuring a plurality of parameters associated with the at least one node of the first circuit, wherein the first parameter is one of the plurality of parameters; and

wherein the circuitry for comparing the parameter to a configurable parameter range is operable for comparing each parameter in the plurality of parameters to a respective configurable parameter range, wherein the verification sensor is operable to detect the circuit condition indicative of unauthorized use in response to a determination from the comparing that any parameter in the plurality of parameters is outside the respective configurable parameter range.

35. The tamper-resistant circuitry of claim 32 wherein the event comprises receiving, by the electronic device, data that is transmitted from externally to the electronic device.

36. The tamper-resistant circuitry of claim 35 wherein the data is selected from the group consisting of voice data, video data, text data, and control data.

37. The tamper-resistant circuitry of claim 32 wherein the event comprises an event occurring in response to a time programmed into the electronic device.

38. The tamper-resistant circuitry of claim 32 wherein the electronic device is selected from the group consisting of a cellular telephone, a personal digital assistant, a content player, a pager, a video game player, an email communication device, and an alarm clock.

39. The tamper-resistant circuitry of claim 32 wherein the electronic device is operable with power from a battery.

40. The tamper-resistant circuitry of claim 32 wherein:

the first circuit includes a plurality of circuits each operable to change a respective signal state in response to an event; and

the verification sensor circuit including a plurality of verification sensors coupled to the first circuit, wherein each verification sensor in the plurality of verification sensors is operable to detect a circuit condition outside the configurable parameter range and upon detection of the circuit condition to prevent the change of the respective signal state.

41. Tamper-resistant circuitry for inclusion in an electronic device, the tamper-resistant circuitry comprising:

a display operable to provide illumination;

an optical detector element; and

a circuit for disabling the display from providing illumination in response to determining that the optical detector element detects an insufficient amount of light.

42. The tamper-resistant circuitry of claim 41 and further comprising a circuit for emitting light, wherein the circuitry for emitting light is positioned relative to the optical detector element so that light emitted by the circuitry for emitting is not detectable by the optical detector element unless reflected to the optical detector element by an external object.

43. The tamper-resistant circuitry of claim 42 wherein the circuit for disabling is operable to forego the disabling in response to an instance of both determining that the optical detector element detects an insufficient amount of light when the circuitry for emitting is not emitting light and determining that the optical detector element detects an insufficient amount of light when the circuit for emitting is emitting light.

44. The tamper-resistant circuitry of claim 42 wherein the circuit for disabling is operable to disable the display from providing illumination in response to an instance of both determining that the optical detector element detects an insufficient amount of light when the circuitry for emitting is not emitting light and determining that the optical detector element detects reflected light when the circuitry for emitting is emitting light.

45. The tamper-resistant circuitry of claim 42 wherein the circuit for emitting light provides a low light level relative to the illumination that the display is ordinarily operable to provide.

46. A portable electronic device, comprising:

wireless receiving circuitry operable to receive an incoming communication;

a first circuit operable to change a signal state in response to the incoming communication; and

a verification sensor circuit coupled to the first circuit and operable to detect a circuit condition indicative of unauthorized use and upon detection of the circuit condition to prevent the change of the signal state.

47. The portable electronic device of claim 46 wherein the first circuit is operable to provide functionality selected from a set consisting of a cellular telephone functionality, personal digital assistant functionality, music player functionality, pager functionality, video game player functionality, email communication, and alarm functionality.

48. A portable electronic device, comprising:

circuitry for receiving power;

a first circuit operable from the power and operable to change a signal state in response to an event; and

a verification sensor circuit coupled to the first circuit and operable to access a parameter range and to detect a circuit condition outside the parameter range and upon detection of the circuit condition to prevent the change of the signal state in response to the event.

49. The portable electronic device of claim 48 wherein the first circuit is operable to provide functionality selected from a set consisting of a cellular telephone functionality, personal digital assistant functionality, music player functionality, pager functionality, video game player functionality, email communication, and alarm functionality.

50. A method of reducing an opportunity for tampering of circuitry in an electronic device, comprising:

receiving an incoming wireless communication for provoking a change of a signal state by a circuit in response to the incoming wireless communication; and

detecting a circuit condition indicative of unauthorized use and upon detection of the circuit condition preventing the change of the signal state by the circuit.

51. The method of claim 50 wherein the detecting comprises loading a node in the circuit with different impedances and measuring a respective resultant parameter associated with the node for each of the different impedances.

52. The method of claim 50 wherein the detecting comprises driving a node in the circuit with different frequencies and measuring a respective resultant parameter associated with the node for each of the different frequencies.

53. The method of claim 50 wherein the detecting comprises:

measuring a parameter associated with at least one node of the circuit; and

comparing the parameter to a range of acceptable values, wherein the detecting detects the circuit condition indicative of unauthorized use when the parameter is outside the range of acceptable values.

54. The method of claim 53:

wherein the measuring is for measuring a plurality of parameters associated with the at least one node of the circuit; and

wherein the comparing is for comparing each parameter in the plurality of parameters to a respective range of acceptable values, wherein the detecting detects the circuit condition indicative of unauthorized use when any parameter in the plurality of parameters is outside its respective range of acceptable values.

55. The method of claim 53 further comprising adjusting at least one value affecting the range of acceptable values in response to a variable affecting the parameter.

56. The method of claim 50 wherein the change of signal state is for causing operation of a circuit selected from the group consisting of a ringer, a vibrator, a display, a light, a motor, a driver, an amplifier, an LED, an interface, a DTMF input, a DTMF output, and a headphone/earphone.

57. The method of claim 50 wherein the incoming communication comprises data selected from a set consisting of voice data, video data, text data, and control data.

58. The method of claim 50 wherein the detecting is responsive to evaluating a measured parameter that is selected from a set consisting of a voltage, current, impedance, a change in voltage, a change in current, and a change in impedance.

59. A method of reducing an opportunity for tampering of a circuit in an electronic device, comprising:

in response to an event, calling upon a circuit to change a signal state; and

accessing a parameter range; and

detecting whether a circuit condition is outside the parameter range and, if outside, then preventing the change of the signal state.

60. The method of claim 59 wherein the detecting comprises:

measuring a parameter associated with at least one node of the circuit;

comparing the parameter to the parameter range to detect whether the circuit condition is outside the parameter range.

61. The method of claim 59 wherein the event comprises receiving, by the electronic device, data that is transmitted to the electronic device.

62. The method of claim 59 wherein the event comprises an event occurring in response to a time programmed into the electronic device.

63. The method of claim 59 wherein the electronic device is selected from a set consisting of a cellular telephone, a personal digital assistant, a music player, a pager, a video game player, an email communication device, and an alarm clock.