A compact disk includes a processor and a transmission element under control of the processor. A laser in a compact disk read head illuminates a photosensitive array disposed on the compact disk to generate a current in a charging array. The current generated in charging array is supplied to a storage element. The storage element supplies the processor with power. The processor controls a transmission element electrically coupled to the processor and optically coupled to the compact disk reader to impart an informational signal to the compact disk reader such as a cryptographic key to control utilization of the contents of the CD. The CD can be written to by the CD controller by having the CD read circuit control the light provided to the photosensitive array to impart an information signal to the photosensitive sensitive array. A circuit is coupled to the light sensitive array to time the on and off state of the current supplied to the light sensitive array and to thereby detect the informational signal from the compact disk reader circuit.