| 摘要 |
PROBLEM TO BE SOLVED: To perform secure data transmission between terminals through a network by storing 1st and 2nd keys and generating each partial key of the 1st and 2nd keys as a function whose common number is separately is masked and also as a corresponding key among stored keys. SOLUTION: Each terminal 2 has a related special terminal key. The terminal key is stored in an SIM, that is contained in the terminal and also in a central database station 15. A cryptographic key KR to be used is a function of a random number (RAND), that is generated by the station 15 separated far away. The station 15 distributes a random number (RAND) in a masked form (part keys kpa and Kpb) to terminals 2a and 2b. Sending terminal keys in a masked from prevents a person who intercepts from accessing each terminal key. Changing a mask in each section operation prevents the eavesdropper from knowing a mask function. |
