Patent ID: 7590842

Claim:
A service providing system, comprising: a signature generating apparatus; a service utilizing apparatus; a verification apparatus; and a service providing apparatus, wherein said signature generating apparatus, comprises: a communicating means; a key producing means for producing a generation key for generating an electronic signature and a verification key for verifying righteousness of the electronic signature produced by using said generation key, in a pair; a memory means for holding said generation key; and a signature generating means for generating the electronic signature, by using an arbitrary number received from said service utilizing apparatus and the generation key, whereby transmitting the electronic signature to said service utilizing apparatus and also transmitting the verification key to said verification apparatus; said service utilizing apparatus, comprises: a communication means; a service request means for requesting a service to be utilized; and a service utilization means for utilizing a response to said service request, thereby transferring the arbitrary number received from the verification apparatus to the signature generating apparatus, and the electronic signature received from said signature generating apparatus to said verification apparatus, while transmitting the request for the service to be utilized to the verification apparatus; said verification apparatus, comprises: a communication means; an arbitrary number producing means for producing an arbitrary number to be used by the signature generating apparatus in generation of the electronic signature; a memory means for holding the verification key received from the signature generating apparatus; and a signature verification means for verifying the electronic signature by using said arbitrary number and said verification key, whereby transmitting said arbitrary number to the service utilizing apparatus, transferring the service request received from said service utilizing apparatus to said service providing apparatus, when the electronic signature, which the service utilizing apparatus transfers by using said signature verification means, is correctly verified, and transferring a response to the service request received from said service providing apparatus to said service utilizing apparatus; and said service providing apparatus, comprises: a communication means; and a service execution means for executing service responding to the service request, whereby turning a result of execution of the service responding to the service request transferred from the verification apparatus back to said verification apparatus as a response to the service request.