A network transaction system applicable to cyberspace banking services using
an
open network, which allows customers to authenticate themselves through a simplified
procedure. A customer's terminal station and a plurality of bank systems are interconnected
via networks, and it is assumed that the customer wishes to newly open a bank account
in a bank system among them, or a target bank system, and that the customer has
an existing bank account in a different bank system, or an cooperative bank system.
Using his/her terminal station, the customer applies for a new bank account by
supplying the target bank system with a ciphertext message containing existing
account information descriptive of the customer's bank account in the cooperative
bank system. The target bank system requests the cooperative bank system to confirm
the customer's existing bank account, while forwarding thereto a part of the ciphertext
message containing the existing account information. The cooperative bank system
decrypts the received message and confirms the validity of the account that the
customer claims to own. It then returns a response message to the target bank system
to report the result of the account confirmation. The target bank system decides
whether to accept or to reject the application for a new account based on the response
message from the cooperative bank system.
