Abstract: A private security code used for rendering microprocessor-based electronic equipment operational need not be selected or remembered by the user of the equipment. Instead, an authorized service center generates the private security code needed to re-enable disabled equipment. The equipment includes a built-in microprocessor for executing a program stored in internal memory, a random number generator for generating an unpredictable code, and a display for displaying the unpredictable code. The microprocessor also executes an encryption routine for encrypting the unpredictable code and storing the encrypted code in the internal memory protected from exterior interrogation. The service center generates the same encrypted code in response to knowledge of the displayed unpredictable code. Entry of the same encrypted code via a keyboard into the disabled equipment re-enables the same.