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 staff alpha and a staff beta belonging to the same project group, alpha of the transmission side writes an arbitrary variable code V( 1 ) in the IC card ( 100 a) so as to generate encryption key information K(a 1 ) according to F(a) and V( 1 ) in the IC card and encrypt data D 1 by using K(a 1 ). beta of the reception side writes the variable code V( 1 ) received from a in the IC card ( 100 b) so as to generate encryption key information K(a 1 ). By using this K(a 1 ), the encrypted data D 2 received is decrypted to obtain data D 3 . The fixed code F(a) is different for each of the companies and rewrite-disabled so as to assure security.