Trustworthy timestamps and certifiable clocks using logs linked by cryptographic hashes
First Claim
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1. A method comprising:
- maintaining, by a device that logs event times and document hashes, a first log of the event times and document hashes in a chained-hash format;
associating, by the device, a first clock with the first log;
entangling, by the device, the first log with a second log maintained by another device by adding a time-stamped synchronization entry to the first log, the time-stamped synchronization entry having a time indication associated with a second clock from the another device maintaining the second log and a hash of the second log, wherein the second clock from the another device is a trustworthy clock;
tracing, by the device, the entangling of the first log back to the second clock that is trustworthy;
determining, by the device, a level of accuracy of the first clock based on an assessment of accuracy of the second clock that is trustworthy; and
determining reliability of timestamps in the first log based on observed accuracy of the second clock and a reputation of the another device that maintains the second log.
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Abstract
A method and apparatus for creating and/or using trustworthy timestamps and certifiable clocks using logs linked by cryptographic hashes. In one embodiment, the method comprises maintaining a first, chained-hash log; associating a first clock with the chained-hash log, and entangling the first log; with a second by adding a time-stamped synchronization entry to the chained-hash log, where the synchronization entry has a second time indication associated with the second log and a hash of one or more entries in the first log.
132 Citations
22 Claims
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1. A method comprising:
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maintaining, by a device that logs event times and document hashes, a first log of the event times and document hashes in a chained-hash format; associating, by the device, a first clock with the first log; entangling, by the device, the first log with a second log maintained by another device by adding a time-stamped synchronization entry to the first log, the time-stamped synchronization entry having a time indication associated with a second clock from the another device maintaining the second log and a hash of the second log, wherein the second clock from the another device is a trustworthy clock; tracing, by the device, the entangling of the first log back to the second clock that is trustworthy; determining, by the device, a level of accuracy of the first clock based on an assessment of accuracy of the second clock that is trustworthy; and determining reliability of timestamps in the first log based on observed accuracy of the second clock and a reputation of the another device that maintains the second log. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method comprising:
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synchronizing, by a device that logs event times and document hashes, a first hash-chained log with a second hash-chained log by adding a time-stamped log entry into the first log containing a first time indication of a clock associated with the second log; producing, by the device, one or more document timestamps that are traceable to a trusted clock source by referencing a cross-connection of the first and second logs created by the synchronization of the first log with the second log; and determining, by the device, a level of accuracy of the clock based on an assessment of accuracy of a clock of the trusted clock source; and determining reliability of timestamps in the first log based on observed accuracy of the second clock and a reputation of the another device that maintains the second log. - View Dependent Claims (16, 17)
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18. A method comprising:
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exchanging, by a first device that logs event times and document hashes, log information to synchronize a pair of hash-chained logs that each have clocks used for time-stamping entries in each hash-chained log; and placing, by the first device, a bound on accuracy of a clock associated with a first log in the pair of logs based on an assessment of accuracy of a clock associated with a second log in the pair of logs; wherein reliability of timestamps in the first log is based on the assessed accuracy of the second clock and a reputation of a second device that is considered trustworthy and that maintains the second log. - View Dependent Claims (19, 20, 21, 22)
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Specification