A signature
verification system includes a signature generation
server, a signature
verification server, and a
verification key management server that are connected to one another via a communication network. The signature generation server includes: reporting means for, when a signing key and a verification key are generated by a publisher, reporting the verification key and publisher identification information that identifies the publisher to the verification
key management server; and signature generation means for signing a bid request issued by the publisher with use of the signing key. The verification
key management server includes: registration means for registering the publisher identification information and the verification key that were reported by the reporting means in a storage unit in association with information that enables specifying a version of the verification key; verification means for, upon receiving publisher identification information and a name indicating a verification key from the signature verification server, verifying whether or not a verification key that corresponds to the received publisher identification information and name and that is a latest version is registered in the storage unit; and first transmission means for, if the verification means verified that the verification key that is the latest version is registered in the storage unit, transmitting the latest-version verification key to the signature verification server. The signature verification server includes: second transmission means for, upon receiving the bid request, transmitting publisher identification information and a name indicating a verification key that are included in the bid request to the verification key management server; and signature verification means for, if the publisher identification information and the name were transmitted by the second transmission means and the latest-version verification key was received from the verification key management server in response, performing verification of the bid request with use of the latest-version verification key.