Abstract: This invention is intended for the communication between a first communication device (e.g., an IC card) and a second communication device (e.g., a card terminal) by preventing the faking of the IC card or card terminal, for example, thereby allowing correct information exchange between them. The invention provides the IC card with a first encryption means and the card terminal with a second encryption means. In consequence, communication signals in both directions are encrypted, and random numbers and the algorism of functional computation are prevented from being analyzed. As a result, manufacturing of fake devices can be prevented and correct information exchange can be performed.

Abstract: A method of making MOS integrated circuits employs high-pressure oxidation of the surface of a silicon slice to create thermal field oxide for device isolation. The implant used prior to this oxidation to provide the channel-stop regions beneath the field oxide may be at a lower dosage, and yet the field-transistor threshold voltage is maintained at a high level. Thus, encroachment of the channel stop impurity into the transistor channel is minimized, and higher density devices are permitted.