Time stamping system
First Claim
1. A time-stamping device for digitally time-stamping input data, comprising:
- (a) a free-running timer having a timer output;
(b) a memory means for storing a plurality of sets of timer calibration information, each defining characteristics of a respective virtual clock;
(c) means for calibrating each virtual clock by updating the respective timer calibration data set in the memory means;
(d) compensation means for receiving the timer output and, for a given user-selected virtual clock, applying the respective timer calibration data set thereto to adjust said output and to generate a corresponding selected virtual clock output; and
(e) signature means for generating a time-stamped output in dependence upon the selected virtual clock output and the input data.
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Accused Products
Abstract
A secure time stamping device uses multiple virtual clocks, each of which may be individually accessed and calibrated. A digital key is associated with each of the clocks. All of the virtual clocks use a common timer (130), with the actual clock output being generated by applying calibration information (124) for that clock to the timer (130) output. A user wishing to have a message time stamped presents that message along with information as to which virtual clock to be used at a device input (92). The appropriate calibration information (124) is then selected and the timer (130) output is compensated accordingly. The incoming message plus the resultant time are concatenated and automatically signed using the key (126) applicable to that particular virtual clock.
20 Citations
15 Claims
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1. A time-stamping device for digitally time-stamping input data, comprising:
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(a) a free-running timer having a timer output; (b) a memory means for storing a plurality of sets of timer calibration information, each defining characteristics of a respective virtual clock; (c) means for calibrating each virtual clock by updating the respective timer calibration data set in the memory means; (d) compensation means for receiving the timer output and, for a given user-selected virtual clock, applying the respective timer calibration data set thereto to adjust said output and to generate a corresponding selected virtual clock output; and (e) signature means for generating a time-stamped output in dependence upon the selected virtual clock output and the input data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of digitally time-stamping input data, comprising:
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(a) selecting one set of timer calibration data from a plurality of such stored sets, each set defining the characteristics of a respective virtual clock; (b) adjusting an output of a free-running timer by applying a respective timer calibration set thereto to generate a corresponding selected virtual clock output; and (c) signing data representative of both the selected virtual clock output and the input data to generate a time-stamped output. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification