The invention uses a new process called dynamic pin reassignment (DPR) to alter the circuitry. The system assigns input and output signals to buses that lead to a central distribution point, the crossbar, in the circuit. At the crossbar, signals are routed to the appropriate destination over one of the bus wires to the correct chip from the crossbar. At irregular intervals, the signal mapping for each in/out function is changed. The assignments or mappings, comprise the state of the circuit at any time. The period that a state is valid is determined by applying a reseeding function to a portion of a randomized stream that calculates the next state and the duration of validity. Multiple seeds or keys are used to create the states. Because each key changes independently of the other keys and without notice, the time interval for a valid state is greatly reduced, complicating any effort to reveal the internal states of chips.