| 摘要 |
PURPOSE:To reduce the burden on a host device by permitting one host to handle plural IC cards so as to construct an online system and storing a common session key common to respective IC cards at the time of operating the session key. CONSTITUTION:The host device 2 and electronic devices such as respective IC cards 1, and 4 store the previously decided single session key. In respective sessions, the host device 2 and the electronic devices hold same transmission data obtained as the result of the session as a key for encoding/decoding, cipher the session key from the host device 2 to the electronic devices by using transmission data after the final session. The side of the electronic devices decodes data and hold it. Thus, a data communication system using the session key without the burden on the host device 2 can be obtained. |
