Improved security system for a portable data carrier

Abstract

A portable data carrier system provides improved security for files which support multiple applications, from custom repertory dialing to storage of individual medical and/or banking records. Included in the system is a portable data carrier which looks and feels much like an ordinary credit card. The portable data carrier, however, includes a computer and an electrically erasable field programmable read-only memory. Power for operation of the portable data carrier is provided from an associated station via a reader/writer. The reader/writer also couples data between the data carrier and the associated station. Operation of the data carrier is through an executive operating system that is accessed from the station via a set of commonly understood command primitives. These command primitives manipulate the files in the data carrier in accordance with security requirements. Security is enhanced since the stations's application software receiving and interpreting the data from a file sees a contiguous stream of bytes relating only to the file of the application being accessed. No information is provided to a user of a particular application about other applications in the data carrier or about the data carrier's internal file structure.