| Along with the encryption technology unceasing development and progress, and the expanding of applied range, all kinds of encryption algorithm and the realization technology of encryption algorithm had been research and applied. In the vehicle GPS locating system, the vehicle location information delivered by satellite had been encrypted and transmitted to system terminal through wireless network. It would be convenience for vehicle monitor and management. Meanwhile the vehicle GPS information would be protected from illegal interception and manipulation. AES encryption algorithm was used increasingly because its advantage of high coding efficiency, low memory requirements, restricted environment suited, long key. At the same time FPGA technology had become the primary technology to realize encryption algorithm for its advantage of in system programmability and easy updating.Through analyzing the existing embedded development platform, vehicle GPS data encryption scheme had been established based FPGA. The development, debugging and updating of GPS encryption system would be much easier by FPGA. Blue hurricane Cyclone â…¡ development board had been chosen as development and testing environment. The version was EP2C35F672C8. Quaturs9.0and IDE9.0were chosen as software and hardware platform to design the system. Verilog hardware language and C based Nios â…¡ were chosen as the programming language.About the system construction, RS-232communication protocol had been used to receive and send data. SOPC Builder had been adopt to set up hardware environment include CPU and peripheral etc. The data loading and encrypting was controlled by CPU. As a separate module, AES algorithm would be realized by hardware language to improve the system encryption speed. Finally, the complete system would established through connect the encryption module, the module set up by SOPC Builder, the SDRAM storage module, and associated peripherals.The encryption module was core part of GPS encryption system. Based the traditional AES algorithm, this paper proposed a modified AES algorithm and its implement method according to the software and hardware environment. In AES algorithm, sub-bytes and shift-row step were merged to shift-sub. The rapid processing of bytes was implement take advantage of parallel behavior of Verilog language. In mixcolumn step, a LUT based mixcolumn improved method was given. Using LUT technology, the domain multiplicative operation would convert to bytes loading operation. The experimental results showed that given method could improve the encryption speed effectively. The security and real-time capability of vehicle GPS encryption system were fulfilled. In the end, GPS encryption system was verified through testbench document and Modelsim simulation software. The compilation report showed that proposed encryption method could improve the encryption speed without affecting its security. The system could satisfy the security and real-time capability. |
