Software protection method and apparatus

A system for protecting computer software, comprising:

• a microprocessor configured to execute a control program, said program including means for generating a control signal;
• a key having a preselected one of a plurality of charging and discharging characteristics associated therewith;
• and
• protection means responsive to said control is coupled to said key for electrically stimulating said key, for said preselected charging and discharging characteristic in response thereto, and for generating a signal indicative of said characteristic, said protection means further having means for said generated characteristic indicative signal to said executing on said microprocessor,
• said program further including means for disabling use of the protected software using, in accordance with predetermined criteria, said characteristic indicative signal.

A method of protecting computer software in a system of the type including a key having a capacitor with an initial charge associated therewith, and a protection device having a switch coupled to the key, comprising the steps of:

• (A) altering the charge on the capacitor from the initial amount to a second amount by turning on the switch;
• (B) altering the charge on the capacitor from the second amount towards the initial amount by turning off the switch;
• (C) determining a time for the charge on the capacitor to reach predetermined threshold level wherein the predetermined threshold level has a value intermediate the initial amount and the second amount;
• (D) disabling use of the protected software using the time determined in step (C), in accordance with predetermined criteria.