| 摘要 |
<p>An automatic collection system for automatically collecting a toll charge from an IC card (2) is provided with transceivers (32, 34, 42, 44) in gantries (30, 40) installed along a vehicle road. This collection system uses the transceivers (32, 34, 42, 44) to perform communication with a vehicle-mounted device (10) based on the use of encrypted data. The vehicle-mounted device (10) performs the encryption and decryption of the communication data before its entry into the communication area of the gantries (30, 40) and after its passage therethrough. Also, writing of the data into the IC card (2), etc. are also performed using encrypted data. However, an algorithm which differs from that used in encrypting the data stored in the IC card (2) and which enables the execution of the high speed processing is used for encrypting the communication data. As a result, since the encryption and decryption of the data is performed only in the roadside device (20) side during communication and this encryption and decryption can be performed at a high speed, the communication time can be shortened to perform accurate data communications within a limited period of time while the vehicle is travelling. <IMAGE></p> |
