SHARED KEY GENERATING METHOD, SHARED KEY GENERATING SYSTEM, ENCRYPTED DATA COPYING METHOD, SHARED KEY GENERATING PROGRAM, ENCRYPTED DATA TRANSMISSION PROGRAM, AND ENCRYPTED DATA RECEPTION PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a shared key generating method whereby danger of leakage of a shared key used for encrypting data is less. SOLUTION: The shared key generating method is used by a terminal A being a small-sized communication terminal such as a mobile phone with high tamper resistant performance and by a terminal B such as a PC with low tamper resistant performance. The terminal A generates a partial key Kp by using a key generating function F1 on the basis of terminal information unique to the terminal. Succeedingly, the terminal A generates the shared key K by using a key generating function F2 on the basis of the generated partial key Kp and a private key Kc and encrypts/decrypts the data by using the generated shared key K. On the other hand, the terminal A transmits the generated partial key Kp to the terminal B. When receiving the partial key Kp, the terminal B generates the shared key K on the basis of a private key Kc_2 shared with the terminal A and the partial key Kp. COPYRIGHT: (C)2007,JPO&INPIT