Design And Implementation Of GPS Information Encryption And Transmission System Based On CDMA

In a sham battle or real war, in order to direct the war better, headquarters need to be in control of the battlefield situation and the information of the vehicle equipments' location. In this case, it is impossible to use the wire communication. A set of wireless communication system is needed, which can transmit the global position information of the vehicle equipments after encryption through the wireless channel to the headquarters. The system can not only be used in the sham battle or battlefield, its function can also be enlarged. For instance, it can be fixed in the cipher box or cipher machine to get the location information of these equipments, especially when removed or taken illegally. Then we can know whether the equipments were taken to the unsafe places and locate the position.On the basis of the consideration above, an on-vehicle system is designed which is based on CDMA wireless channel to transmit the global position information which is encrypted by the ARM microprocessor. We use GPS system to locate the vehicles. The location information is encrypted with AES algorithm in the ARM microprocessor. Then it is sent to the wireless network through CDMA DTU, and is received by the computers in the headquarters.To insure the confidentiality, integrity, usability and undeniable, project of the data delivery on a wireless channel and project of key management were designed. To encrypt the GPS information, 128 bit AES arithmetic was used. The data delivery method combines the characteristics of the data format of the GPS information and the length of the AES arithmetic. Get the GPS information from the GPS module every second, after 4 sets of GPS information were get, the data was encrypted and delivered. In the project of key management, main key, encryption key and conversation key was designed. Consultation of the conversation key is needed before every data encryption, the conversation key can only be used once in the data encryption, and the key will be cancelled after use.This system is implemented based on S3C2410 microprocessor of Samsung Company, the hardware and software of the system was tested, and ARMulator instruction set simulator of ARM Company was used to test and evaluate the efficiency of the arithmetic runing on the microprocessor. The results indicate that the expected target of the system was realized, and the requirements of practically usage can be satisfied.