Patent ID: 7934256

Claim:
An electronic device having an application file pertaining to an operation of application software and updating the application file via a network, comprising: a storage unit storing therein the application file including one or more data pieces; a reception unit operable to receive, from an external apparatus via the network, update data and location information indicating a location in the application file, the indicated location being for rewrite with the update data; an update process unit operable to rewrite only part of the application file by writing over a data piece present at the indicated location with the update data to update the application file; and a tamper detection execution unit operable to examine whether the updated application file has been tampered with, wherein the reception unit receives one or more updating sets, each of which includes the update data and the location information, wherein the update process unit includes: a location determining subunit operable to determine, with respect to each of the updating sets, an update location in the application file based on the indicated location; a write subunit operable to write, with respect to each of the updating sets, the update data in a place starting from the determined update location; and an update control subunit operable to control the location determining subunit and the write subunit to be in process until completion of writing of the update data included in all the sets, wherein the update control subunit controls the tamper detection execution unit to start a process thereof when the writing of the update data included in all the updating sets is completed, wherein the update process unit further includes: a flag storage subunit storing therein a flag showing one of 1 st information indicating that the application file is in a process of update and 2 nd information indicating that the application file is not in the process of update; and a flag change subunit operable to change flag information shown by the flag, wherein the flag change subunit changes the flag information to the 1 st information when the reception unit receives the updating sets, and changes the flag information to the 2 nd information when tampering is not detected by the tamper detection execution unit, and wherein the update control subunit checks the flag information when the electronic device is powered on, and in a case where the flag information is the 1 st information, the update control subunit cause the reception unit to newly receive, from the external apparatus, the update data and the location information, and the update control subunit controls the location determining subunit and the write subunit to be in process after newly receiving the update data and the location information.