To surely assure the accuracy of received data in the case of being attacked by the third party on the transmission path.
When both of a transmission side and a receiver side share secret information common to both particles beforehand, a data source arranged at the transmitter side is provided with a confirmation information calculation means for determining such confirmation information as is calculated by using secret information which only a person concerned can know and is, moreover, calculated 3 by using a one-way function with which it is very difficult to inversely operate original variables from the calculation result, and the confirmation information calculated by this calculation means are sent out in a transmission path by adding it to the data to be transmitted.
NAKAGAWA SATOSHI
TAGAWA TADAMICHI
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