PROXY SERVER, ELECTRONIC SIGNATURE SYSTEM, ELECTRONIC SIGNATURE VERIFICATION SYSTEM, NETWORK SYSTEM, ELECTRONIC SIGNATURE METHOD, ELECTRONIC SIGNATURE VERIFICATION METHOD, RECORDING MEDIUM AND PROGRAM TRANSMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a security function using electronic signature without the need to change application programs, by mounting means, which conduct electronic signature, verification, and logging of messages received/transmitted via networks, in the form of a proxy server. SOLUTION: An application 10, which conducts data processing, and a signature proxy server 20 connected with the application 10 via a LAN 100 are provided. The signature proxy server 20 intercepts message communication from the application 10 to external devices of the LAN 100, conducts electronic signature on message documents in this message communication, and transmits message documents attached with the electronic signature to a device of transmission destination.