Method to securely initialize, protect and recover system date/time
First Claim
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1. A method of protecting a timer on a computer system from being improperly adjusted comprising:
- establishing a baseline value for at least one timer on the computer system;
monitoring the computer system for a timer anomaly that indicates a possible improper timer adjustment; and
imposing a sanction if a timer anomaly is detected.
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Abstract
The claimed method and system monitors computer system timer(s) relative to other timers to detect discrepancies and/or may capture an offset to provide a method of more accurately determining a current time. The invention may also provide a method to detect power source tampering using a last known good time and may provide a means to securely initialize system time using an encrypted time stamp.
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Citations
20 Claims
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1. A method of protecting a timer on a computer system from being improperly adjusted comprising:
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establishing a baseline value for at least one timer on the computer system;
monitoring the computer system for a timer anomaly that indicates a possible improper timer adjustment; and
imposing a sanction if a timer anomaly is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A computer-readable medium having computer-executable instructions for performing operations comprising:
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determining a set of timers in a computer;
measuring a set of frequency differences between the timers in the set of timers;
raising an alarm when one of the set of frequency differences is greater than a threshold.
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19. A computer system comprising:
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a hardware module coupled to a real time clock circuit and having a secure, non-volatile memory, wherein the hardware module provides a register for clock values;
a hardware component that intercepts a clock adjustment signal that is being transmitted to the hardware module, determines a current clock value when the clock adjustment signal is intercepted, and stores an offset in the secure, non-volatile memory, wherein the offset is based on a difference between the current clock value and the clock adjustment signal. - View Dependent Claims (20)
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Specification