Patent ID: 7706574

Claim:
A method performed by a processing device comprising: tracking a first time interval that a computer system input source is active; tracking a second time interval between input source activation; and storing in the computer system at least one biometric keystroke user identification template derived from the first time interval and the second time interval, wherein the first time interval and second time interval: (1) are associated with a first diagraph defined by a common sequence of letters that occur during typing of separate letters of the first diagraph and (2) depend on a typing characteristic of a user, wherein the first time interval is an interval that a first key of the first diagraph is active, the second time interval is an interval between input source deactivation of the first key and input source activation of a second key of the first diagraph; and further comprising tracking a third time interval that the computer input source is active for the second key of the first diagraph, wherein deriving the user identification template comprises calculating a template interval mean using the first, second, and third time interval to measure the proximity of the first, second, and third time interval with a plurality of previously tracked first, second, and third time intervals; wherein the computer system input source is an alpha-numeric keyboard.