| 摘要 |
PROBLEM TO BE SOLVED: To prevent a third person from decoding a cryptography intercepted from a communication network by recording plural user secret keys in the relation of a pair with user open keys held in respective user terminals in the memory of a host computer, in a state where they are open key-ciphered through the use of a master open key. SOLUTION: When an arbitrary terminal arbitrarily decides a data ciphering key KS and he is to share it with a user A using a host system 115, RSAHP1 (KS) is calculated by using an open key HP1 and is transmitted to the user A of the host system 115. When the user A receives RSAHP1 (KS), he by making makes an access a memory 125, he obtains RSAHPM (HS1). Thus, EKM (KS) can be obtained in a host main body by the processing of a ciphering machine 119. Then, the data ciphering key KS can be shared with the terminal. Then, EKM (KS) held by the host main body 116 is deleted after communication terminates.
|
