| 摘要 |
<p>The present invention relates to security technology for information devices such as cellular phones, personal computers and the like. More specifically, the present invention is intended to provide a technique capable of restricting the use of or removing the restrictions on the use of information devices with a low-cost configuration. In order to realize this object, a key system (100) includes a key device (1), and a cellular phone (11) capable of being locked or released from the lock by the key device (1). An LED (4) of the key device (1) and an LED (14) of the cellular phone (11) are capable of sending data therebetween, and key information is sent from the LED (4) to the LED (14). The cellular phone (11) is locked or released from the lock based on the key information received by the LED (14).</p> |
