Device for controlling communication between electronic information cards and host computer to be kept in secret

A system for controlling communication between an electronic information card including contacts and a host computer for reading and writing data to and from the electronic information card via a communication cable, said system comprising;

• a first terminal connector, connected to the communication cable for receiving information including data and signals transmitted from the host computer;
• a second terminal connection, connected to the communication cable for transmitting information including data and signals on the electronic information card to the host computer;
• at least two card connectors, each having contacts corresponding to the contacts of the electronic information card and each having a card detector for generating signals representing a presence and absence of a card therein, wherein
• one of the card connectors receives a card storing at least one fixed communication algorithm, and the other receives the electronic information card such that data stored in the electronic information card is enciphered and deciphered according to the at least one fixed communication algorithm by passing the data through the card storing the at least one fixed communication algorithm;
• means for controlling the communication in response to the signals from the at least two card connectors so as to connect and disconnect circuits between the first and second terminal connectors and the at least two card connectors and between the means for controlling and the at least two card connectors;
• and
• switching means, between the at least two card connectors, and also between each of the at least two card connectors and each of the first and second terminal connectors, and also between each of the at least two card connectors and the means for controlling, so that the means for controlling turns predetermined switches ON and OFF in response to a signal from each of the at least two card connectors and the host computer.