IC CARD FOR ENCRYPTION OR DECRYPTION PROCESS AND ENCRYPTED COMMUNICATION SYSTEM AND ENCRYPTED COMMUNICATION METHOD USING THE SAME

摘要

It is possible to perform encrypted communication between members of a group while assuring a sufficient security compatible with a change of the members. An IC card having the same fixed code F(a) is distributed to all the staffs of company A. When communication is performed between a staffαand a staffβbelonging to the same project group,αof the transmission side writes an arbitrary variable code V(1) in the IC card (100a) so as to generate encryption key information K(a1) according to F(a) and V(1) in the IC card and encrypt data D1 by using K(a1).βof the reception side writes the variable code V(1) received fromαin the IC card (100b) so as to generate encryption key information K(a1). By using this K(a1), the encrypted data D2 received is decrypted to obtain data D3. The fixed code F(a) is different for each of the companies and rewrite-disabled so as to assure security.