Abstract: The present invention provides a service system using a certificate which is easily portable and difficult to counterfeit. The feature of the invention is to use a contactless IC chip as a portable certificate. An IC chip-attached seal is thin and small, and therefore is easily portable and distributable to a user. By integrating or attaching (or sticking) the IC chip into or on a certificate 3910, the counterfeiting of the certificate 3910 becomes difficult.

Abstract: A contactless IC chip is mounted or adhered on a certificate and used in a service system having an interrogator and a computer system. The interrogator and the computer system are interconnected via a network such as the Internet. The IC chip is used as an electronic tag and the interrogator receives first information by reading information printed on the certificate including a digital signature and by receiving second information from the electronic tag through an antenna of the interrogator. Then, the first information from the certificate and the digital signature are used by the computer to calculate third information that is compared with the second information received from the electronic tag. If the comparison results in a match, then the certificate is deemed authentic.

Abstract: The present invention provides a service system using a certificate which is easily portable and difficult to counterfeit. The feature of the invention is to use a contactless IC chip as a portable certificate. An IC chip-attached seal is thin and small, and therefore is easily portable and distributable to a user. By integrating or attaching (or sticking) the IC chip into or on a certificate 3910, the counterfeiting of certificate 3910 becomes difficult.