Research On The Application Of AES In CBTC

Communication Based Train Control (CBTC) system can supervise and control train operation by means of tracking train locations and sending control informations to trains. By EN50159, Data communication system (DCS) by which we can send informations between train and wayside is an open transmition system. So we have to take some measures to ensure the security of DCS.Advanced Encryption Standard (AES) will become the new encryption standard of information security technology. Its block length is 128bits and key size is 128bits, 192bits or 256bits. Its design is simple, key setup time is fine, memory requirtment is low. It support Pipelining and is suited to be implemented on a wide range of processors and in dedicated hardware. What is the most important is AES can resist all known attack efficiently.In this paper, we implemented AES cipher algorithm based on FPGA to ensure both the security and the real time satisfy what the CBTC requests.This paper discussed the theory of AES algorithm, described round function and key expension encipherment, and then presented two implemental ways based on FPGA: serial processing and pipelining. It described the structure and algorithm flow using the hardware description language (VHDL). Then based on the chip of Altera's Stratix and Stratix II, using top-down design method, it partitioned the algorithm into several modules and descrbed the realization of each module in detail. Finally it was simulated in Quartus II 5.1 environment and correct results were obtained.