CONTACTLESS DATA COMMUNICATION SYSTEM AND DATA COMMUNICATION METHOD USING THE SAME SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an RFID system which can add security without increasing the chip area nor the power consumption and a data communication method which uses the system. SOLUTION: The RFID system which sends a packet back at least two times or more from a tag in response to the power-on reset signal of the power source or a polling signal sent from a reader measures communication intervals of packets unique to the tag changing according to manufacture variance of an IC built in the tag, compares the measured value with a value written explicitly or significantly to the tag, and approves the tag when the both match each other. Even when pseudo-random values which are different by tags are used and then when the tag is copied by illegally reading the data out of the tag, the tag can securely be identified to effectively exhibits a security function against an illegal action which can not be prevented by security using an artificially generated value.