Authenticated time device

• US 6,442,691 B1
• Filed: 02/27/1995
• Issued: 08/27/2002
• Est. Priority Date: 07/05/1989
• Status: Expired due to Fees

• Current Assignee: E-Contact Technologies LLC (Empire IP LLC)
• Original Assignee: Robert Roy Blandford
• Inventors: Blandford, Robert Roy
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/394,954
• Time in Patent Office: 2,738 Days
• Field of Search: 380/25, 380/23, 380/45, 380/30, 380/51, 395/425, 364/DIG.1, 364/DIG.2, 340/825.34, 340/5.8, 713/178
• US Class Current: 713/178
• CPC Class Codes: G06F 16/9024 Graphs; Linked lists G06F16/9027 takes precedence
• CPC Class Codes: G06F 21/34 involving the use of external additional devices, e.g. dongles or smart cards
• CPC Class Codes: G06F 21/87 by means of encapsulation, e.g. for integrated circuits
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

A computer diary archives a diary entry by creating, time stamping, authenticating and permanently storing a reference data block along with each diary entry. An archived diary entry can only be modified by placing original text within compartment codes, such as cross-out or tear-out codes, and by placing inserted text within insertion codes so that the original diary entry can be recreated from the modified diary entry. The reference data block, which can be the original diary entry, a canonical version of the original diary entry, or a one way fixed length encryption (hash) of the original diary entry, cannot be modified and is used to authenticate the original diary entry.

The diary program also monitors text entry for aliases and relative date phrases, and upon detection, prompts the user for entry or enters a specific identifier for each detected alias in an alias compartment or an absolute date for each relative date phrase in an implied date compartment in the diary entry.

Claims

1. A method for controlling operation of a user of a user device, comprising the steps of:

(a) issuing an authenticated time signal request from the user device to an authenticated time source device;

(b) generating an authenticated time signal within the authenticated time source device in response to the request;

(c) receiving the authenticated time signal at the user device;

(d) determining, within the user device, the validity of the authenticated time signal;

(e) controlling operation of the user device based on receipt of the authenticated time signal.

2. A method for controlling operation of a user device as recited in claim 1 wherein the step of issuing the authenticated time signal request further comprises the steps of generating a random or pseudorandom number within the user device;

and transmitting the random or pseudorandom number from the user device to the authenticated time source device.

3. A method for controlling operation of a user device as recited in claim 1 wherein the step of generating the authenticated time signal comprises the steps of:

determining a current time;

performing a cryptographic operation on at least the current time to form an authentication code; and

combining at least the current time and the authentication code to produce the authenticated time signal.

4. A method for controlling operation of a user device as recited in claim 3 wherein the step of performing the cryptographic operation further comprises hashing.

5. A method for controlling operation of a user device as recited in claim 3 wherein the step of performing the cryptographic operation comprises using a symmetric or asymmetric cryptographic key protocol.

6. A method for controlling operation of a user device as recited in claim 1 wherein the step of determining the validity of the authenticated time signal further comprises the steps of determining a previous time at which the user device was most recently stopped or started;

determining a returned time from the authenticated time signal; and

verifying that the returned time is later than the previous time.

7. A method for controlling operation of a user device as recited in claim 1 wherein the step of determining the validity of the authenticated time signal comprises the steps of:

determining, from the authenticated time signal, at least a returned time and a returned authentication code;

performing a cryptographic operation on at least the returned time to form a recomputed authentication code; and

comparing the recomputed authentication code and the returned authentication code.

8. A method for controlling operation of a user device as recited in claim 7 wherein said performing the cryptographic operation comprises hashing.

9. A method for controlling operation of a user device as recited in claim 1 wherein the step of determining validity of the authenticated time signal further comprises the steps of:

determining a random or pseudorandom number that was most recently transmitted to the authenticated time source;

determining a returned random or pseudorandom number from the authenticated time signal; and

comparing the returned and most recent random or pseudorandom numbers.

10. A method for controlling operation of a user device as recited in claim 1 wherein the step of controlling operation of the user device comprises setting a clock within the user device upon receipt of a valid authenticated time signal.

11. A method for controlling operation of a user device as recited in claim 1 wherein the step of controlling operation of the user device further comprises preventing continued operation of the user device in the absence of the valid authenticated time signal.

12. A method for controlling operation of a user device as recited in claim 7 wherein said performing the cryptographic operation includes using a cryptographic key.

13. A method for controlling operation of a user device as recited in claim 12 wherein the cryptographic key includes using a key belonging to a symmetric cryptographic protocol.

14. A method for controlling operation of a user device, comprising the steps of:

issuing an authenticated time signal request to an authenticated time-source device;

receiving an authenticated time signal from the authenticated time source device;

determining the validity of the authenticated time signal; and

controlling operation of the user device based on receipt of the authenticated time signal.

15. A method for controlling operation of a user device as recited in claim 14 wherein the step of issuing the authenticated time signal request comprises the steps of:

generating a random or pseudorandom number within the user device; and

transmitting the random or pseudorandom number from the user device to the authenticated time source device.

16. A method for controlling operation of a user device as recited in claim 14 wherein the step of determining the validity of the authenticated time signal comprises the steps of:

determining a previous time at which the user device was most recently stopped or started;

determining a returned time from the authenticated time signal; and

verifying that the returned time is later than the previous time.

17. A method for controlling operation of a user device as recited in claim 14 wherein the step of determining validity of the authenticated time signal further comprises the steps of:

determining, from the authenticated time signal, at least a returned time and a returned authentication code;

performing a cryptographic operation on at least the returned time to form a recomputed authentication code; and

comparing the recomputed authentication code and the returned authentication code.

18. A method for controlling operation of a user device as recited in claim 17 wherein the step of performing the cryptographic operation comprises hashing.

19. A method for controlling operation of a user device as recited in claim 14 wherein the step of determining the validity of the authenticated time signal further comprises the steps of:

determining a random or pseudorandom number that was most recently transmitted to the authenticated time source;

determining a returned random or pseudorandom number from the authenticated time signal; and

comparing the returned and most recently transmitted random or pseudo random numbers.

20. A method for controlling operation of a user device as recited in claim 14 wherein the step of controlling operation of the user device comprises setting a clock within the user device upon receipt of the valid authenticated time signal.

21. A method for controlling operation of a user device as recited in claim 14 wherein the step of controlling operation of the device comprises preventing continued operation of the user device in the absence of a valid authenticated time signal.

22. A method for controlling operation of a user device as recited in claim 17 wherein said performing the cryptographic operation includes using a cryptographic key.

23. A method for controlling operation of a user device as recited in claim 22 wherein the cryptographic key is a key belonging to a symmetric cryptographic protocol.

24. A method for controlling operation of a user device as recited in claim 14 wherein the step of determining the validity of the authenticated time signal further comprises the step of performing a cryptographic operation on the authenticated time signal to give at least a returned time.

25. A method for controlling operation of a user device as recited in claim 24 wherein the step of performing a cryptographic operation includes using a cryptographic key.

26. A method for controlling operation of a user device as recited in claim 25 wherein the cryptographic key is a key used in a symmetric cryptographic protocol.

27. A method for controlling operation of a user device as recited in claim 25 wherein the cryptographic key comprises a key used in an asymmetric cryptographic protocol.

28. A method for controlling operation of a user device as recited in claim 14 wherein the step of determining the validity of the authenticated time signal further comprises the steps of:

determining a random or pseudorandom number that was most recently transmitted to the authenticated time source;

determining a returned random or pseudorandom number from the authenticated time signal; and

comparing the returned and most recently transmitted random or pseudorandom numbers.

29. A method for controlling operation of a user device as recited in claim 14 wherein the step of controlling operation of the user device comprises setting a clock within the user device after receipt of the valid authenticated time signal.

30. A method for controlling operation of a user device as recited in claim 14 wherein the step of controlling operation of the user device comprises preventing continued operation, of the user device unless the valid authenticated time signal is received.

31. An apparatus for controlling operation of a user device, comprising:

an input/output port for issuing an authenticated time signal request to an authenticated time source and receiving an authenticated time signal from the authenticated time source;

a memory;

a controller for determining the validity of the authenticated time signal and for modifying operation of the user device in accordance with the validity determination; and

a tamper resistance system for impeding unauthorized access to the user device.

32. An apparatus for controlling operation of a user device as recited in claim 31 additionally comprising a number generator for generating a random or pseudorandom number as part of the authenticated time signal request.

33. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller comprises:

a comparator for verifying that a returned time, determined from the authenticated time signal, is later than a previous time at which the user device was most recently stopped or started.

34. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller further comprises:

a cryptographic engine for determining a returned time and a returned authentication code from the authenticated time signal, and for performing a cryptographic operation on at least the returned time to form a recomputed authentication code; and

a comparator for comparing the recomputed authentication code and the returned authentication code.

35. An apparatus for controlling operation of a user device as recited in claim 34 wherein the computer engine includes means for computing a hash.

36. An apparatus for controlling operation of a user device as recited in claim 34 wherein the means for cryptographic engine includes at least a cryptographic key.

37. An apparatus for controlling operation of a user device as recited in claim 36 wherein the cryptographic key comprises a key used in a symmetric cryptographic protocol.

38. An apparatus for controlling operation of a user device as recited in claim 36 wherein the cryptographic key comprises a public key used in an asymmetric cryptographic protocol.

39. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller includes a comparator for comparing a first random or pseudorandom number that was most recently transmitted to the authenticated time source device against a second random or pseudorandom number returned from the authenticated time signal.

40. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller comprises means forgetting a clock within the user device upon receipt of a valid authenticated time signal.

41. An apparatus for controlling operation of a user device as recited in claim 31 wherein the controller for modifying operation of the user device comprises means for preventing continued operation of the user device in the absence of the valid authenticated time signal.

42. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises a seal enclosing a clock, a cryptographic engine, an input/output port, a digital bus, and the controller.

43. An apparatus as recited in claim 42 wherein said seal comprises an encapsulation.

44. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises means for allowing only predetermined electronic signals to access the user device.

45. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises means for automatically disabling the user device upon detection of unauthorized access.

46. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller further comprises a cryptographic engine for performing a cryptographic operation on the authenticated time signal to give at least a returned time.

47. An apparatus for controlling operation of a user device as recited in claim 46 wherein the cryptographic engine includes a cryptographic key.

48. An apparatus for controlling operation of a user device as recited in claim 47 wherein the cryptographic key is a key used in a symmetric cryptographic protocol.

49. An apparatus for controlling operation of a user device as recited in claim 47 wherein the cryptographic key is a key used in an asymmetric cryptographic protocol.

50. An apparatus for controlling operation of a user device as recited in claim 31 wherein said controller includes a comparator for comparing a first random or pseudorandom number that was most recently transmitted to the authenticated time source device against a second random or pseudorandom number returned from the authenticated time signal.

51. An apparatus for controlling operation of a user device as recited in claim 31 wherein the controller for modifying operation of the user device comprises means for setting a clock within the user device upon receipt of the valid authenticated time signal.

52. An apparatus for controlling operation of a user device as recited in claim 31 wherein the controller for modifying operation of the user device comprises means for preventing continued operation of the user device in the absence of the valid authenticated time signal.

53. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises a seal for enclosing:

a clock, a cryptographic engine, an input/output port, a digital bus, and the controller.

54. An apparatus for controlling operation of a user device as recited in claim 53 wherein said seal comprises an encapsulation.

55. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises means for allowing only predetermined electronic signals to access the user device.

56. An apparatus for controlling operation of a user device as recited in claim 31 wherein the tamper resistance system comprises means for automatically disabling the user device upon detection of unauthorized access.

57. A device for authenticating and time-stamping input data, comprising:

a clock;

an encryption circuit including a secret key;

an input/output circuit including a port for receiving and transmitting digital signals;

a digital bus coupled to the input/output circuit, the encryption circuit, and the clock;

a controller coupled to the bus for controlling operation of said input/output circuit, said clock and said encryption circuit to receive input data and requests for authenticating and time-stamping the input data applied to the port, to read time data from the clock, to combine and input data with said time data, to operate the encryption circuit to generate an encrypted time stamp authentication code from the combined input data and time data, and to transmit from the port the time data and the encrypted time stamp authentication code; and

an access detector, said access detector indicating attempted access to at least one of said clock, said encryption circuit, said digital bus, said controller, and said input/output circuit except via the port.

58. A device for authenticating and time-stamping input data, comprising:

a clock;

an encryption circuit including a secret key;

an input/output circuit including a port for receiving and transmitting digital signals;

a digital bus coupled to the input/output circuit, the encryption circuit, and the clock;

a controller coupled to the bus for controlling operation of said input/output circuit, said clock and said encryption circuit to receive input data and requests for authenticating and time-stamping the input data applied to the port, to read time data from the clock, to combine and input data with said time data, to operate the encryption circuit to generate an encrypted time stamp authentication code from the combined input data and time data, and to transmit from the port the time data and the encrypted time stamp authentication code; and

an access inhibitor, said access inhibitor impeding access to said clock, said encryption circuit, said digital bus, said controller, and said input/output circuit except via the port.

59. A device for authenticating and time-stamping input data, comprising:

a clock;

an encryption circuit including a secret key;

an input/output circuit including a port for receiving and transmitting digital signals;

a digital bus coupled to the input/output circuit, the encryption circuit, and the clock;

a controller coupled to the bus for controlling operation of said input/output circuit, said clock and said encryption circuit to receive input data and requests for authenticating and time-stamping the input data applied to the port, to read time data from the clock, to combine and input data with said time data, to operate the encryption circuit to generate an encrypted time stamp authentication code from the combined input data and time data, and to transmit from the port the time data and the encrypted time stamp authentication code; and

a tamper resistance system, said tamper resistance system inhibiting undetected access to said clock, said encryption circuit, said digital bus, said controller, and said input/output circuit except via the port.

60. The device of claim 59 wherein said tamper resistance system comprises a seal enclosing said clock, said encryption circuit, said input/output circuit, said digital bus, and said controller.

61. The device of claim 59, wherein said tamper resistance system detects attempted access to at least one of said clock, said encryption circuit, said input/output circuit, said digital bus, and said controller.

62. The device of claim 59, wherein said tamper resistance system impedes access to at least one of said clock, said encryption circuit, said input/output circuit, said digital bus, and said controller.

63. The device of claim 59, wherein said tamper resistance system both detects attempted access to at least one of said clock, said encryption circuit, said input/output circuit, said digital bus, and said controller;

and impedes access to at least one of said clock, said encryption circuit, said digital bus, said controller, and said input/output circuit except via the port.

64. The device of claim 59, wherein said tamper resistance system prevents undetected access to at least one of said clock, said encryption circuit, said input/output circuit, said digital bus, and said controller.