Patent ID: 7512802

Claim:
An application authentication system comprising: a terminal device on which an application is operated; and a secure device connected fixedly or detachably to the terminal device, wherein the terminal device includes: a memory comprising an application recording unit configured to record the application which is operated on the terminal device and performs processing using data held by the secure device; and application running unit configured to run the application, wherein the secure device includes: another memory comprising a data holding unit configured to hold the data used by the application which is operated on the terminal device; verifying unit configured to verify validity of the application running unit and validity of the application; and accepting unit configured to accept access from the application to the data held in the data holding unit when the validities of the application running unit and the application are authenticated, wherein the application running unit calculates digest data of the application and sends the digest data to the verifying unit after the validity of the application running unit is authenticated by the verifying unit, and wherein the verifying unit verifies the validity of the application using the transmitted digest data.