Patent ID: 8122263

Claim:
An application executing method for causing a computer to read and execute an application program from a non-transitory recording medium inserted into the computer, the computer including: a drive unit operable to drive the inserted non-transitory recording medium to read information from the inserted non-transitory recording medium or operable to eject the inserted non-transitory recording medium; and a storage having a storage area specified with a directory for storing a file, and the non-transitory recording medium having recorded thereon: an application containing a target file to be checked for tampering; a first file containing a hash value of the target file; a signature file containing a hash value of the first file; a second file containing (i) a hash value of the signature file, (ii) a first leaf certificate indicating an organization ID, and (iii) a first root certificate related to the first leaf certificate; and a disc root certificate related to the first root certificate, wherein the disc root certificate being a root certificate assigned to the non-transitory recording medium, the application executing method comprising: a reading step of reading information from the inserted non-transitory recording medium driven by the drive unit; a first judgment step of comparing the hash value of the target file contained in the first file with a hash value calculated from the target file to judge whether or not the target file contained in the application has been tampered with; a second judgment step of comparing the hash value contained in the signature file with a hash value calculated from the first file to judge whether or not the first file has been tampered with; a third judgment step of comparing the hash value of the signature file contained in the second file with a hash value calculated from the signature file to judge whether or not the signature file has been tampered with; a fourth judgment step of comparing the first root certificate contained in the second file with the disc root certificate to judge if the two root certificates are identical; an execution step of executing the application; and an allocation step of allocating a storage area in the storage to the application to be executed, the storage area being a storage below a local storage directory corresponding to the hash value of the disc root certificate of the inserted non-transitory recording medium driven by the drive unit, wherein the execution step and the allocation step are performed by the computer, if the judgments in the first, second, third, and fourth judgment steps show that (i) the target file has not been tampered with, (ii) the first file has not been tampered with, (iii) the signature file has not been tampered with, and (iv) the first root certificate is identical to the disc root certificate.