DESIGN OF A SECURE DATA TRANSMISSION SYSTEM:AN IMPLEMENTATION OF COMMUNICATION THEORY USING A MICROCOMPUTER

摘要

This paper describes the development and implementation of a coding technique that provides a high level of security to a system that monitors the status of remote alarm sensor units over physically unprotected lines. It employs nonlinear pseudo¬random sequence generators in both the central and remote units to produce nonrepeating sequences of digits that can be compared. Attempts to penetrate the system alter the transmitted digit sequence, producing a mismatch that sets off the alarm.nLow power CMOS electronics makes it possible to operate the remote nonlinear pseudo-random sequence generators on power supplied over the same unprotected leased telephone lines that carry the data. This unique application of communication theory provides system integrity and secure, reliable monitoring of remote status at moderate cost.