Patent ID: 8141146

Claim:
An authentication server device comprising: an image information storage which stores therein a plurality of image information pieces each containing at least one of one or more known symbols and one or more dummy symbols; a receiver that receives a service use request from a client device via a network; a reading unit that reads one or more of the image information pieces from the image information storage in response to receipt of the service use request; a challenge data creation unit that creates challenge data by using the one or more read image information pieces so that one or more two-dimensional images each containing one or more of the known symbols and one or more two-dimensional images each containing one or more of the dummy symbols presented in turn to the user of the client device, one image at a time; a testing unit that transmits the created challenge data to the client device, and which receives corresponding response data from the client device; and an approving unit that judges whether or not the received response data matches the one or more known symbols contained in the transmitted challenge data, and which approves the service use of the client device when the match is confirmed, wherein the image information storage stores therein a plurality of three-dimensional image information pieces on a three-dimensional object on a surface of which one or more of the known symbols and one or more of the dummy symbols are shown, wherein the reading unit reads one of the three-dimensional image information pieces on the three-dimensional object from the image information storage upon reception of the service use request, and wherein the challenge data creation unit creates a plurality of two-dimensional images of the three-dimensional object seen from different viewpoints, on the basis of the read three-dimensional image information piece, and then creates, as the challenge data, an animation in the animation GIF format, by using the plurality of two-dimensional images.