Research On The Safety Of Message Authentication Code Algorithum In RSSP-?

As the core protocol of signal safety communication in CTCS-3 Train Control System,RSSP-? protocol plays an important role in the safe operation of high-speed railway.Based on the analysis of the RSSP-? railway signal safety protocol,this paper considers that the safety of the encryption algorithm at the bottom of the message authentication code algorithm in RSSP-? needs to be improved.First of all,with the continuous enhancement of computer processing power,DES algorithm with a key length of only 56 bits is no longer considered safe.In July 1998,for example,DES was announced to be broken by a team then called EFF.Secondly,TDES algorithm is currently used as the underlying encryption algorithm of message authentication code algorithm,which is a more safer transformation of DES algorithm.Key K₁,K₂ and K₃determine the safety of TDES algorithm,but the length of plaintext in TDES algorithm is still 64 bits.In terms of safety and efficiency,the length of plaintext packet does not match the growth of key length.Around this problem,this paper puts forward a targeted improvement scheme to provide a higher safety for the train control system signal transmission.First of all,in view of the outstanding performance of advanced encryption standard AES algorithm in safety and efficiency,the innovation of this paper is to introduce advanced encryption standard AES algorithm into message authentication code algorithm in RSSP-? and realize it through FPGA,so as to improve the safety of message authentication code algorithm in RSSP-?.In this paper,the improved MASL-AES-MAC algorithm based on AES algorithm is designed and implemented based on FPGA.In the whole design,the bottom-up and modular design idea is adopted.The design language is Verilog HDL,and the code debugging tool is Quartus ?.After the improved MASL-AES-MAC algorithm adopts FPGA based hardware design,the hardware implementation of the rotation module and the key expansion module in the algorithm is optimized to achieve better time performance.Secondly,the safety of the improved protocol is analyzed theoretically and verified by experiments.The safety of message authentication code algorithm in the improved protocol is analyzed theoretically from two aspects:the safety of encryption algorithm and the residual error probability of message authentication code.Through the formal analysis and modeling tool Casper/FDR,the safety modeling and analysis of the key service process and peer-to-peer entity authentication process in RSSP-? are carried out.Using CSP modeling method to verify the safety of these two processes,and through the state search tool FDR to search the possible state,there is no failed path.It is proved that RSSP-? protocol based on MASL-AES-MAC algorithm meets the safety requirements.Finally,on the basis of proving the protocol safety of the improved optimization algorithm,this paper conducts a joint simulation experiment on the improved message authentication code algorithm in Quartus ? and Modelsim software.After selecting the right test vector and the right chip,the key modules of the hardware design are compiled with test files,followed by function simulation,timing simulation and timing constraints.The simulation results show that the improved MASL-AES-MAC algorithm has higher maximum clock frequency?Fmax?and better real-time performance without increasing the consumption of logical resources.In conclusion,the innovation of this paper lies in the introduction of advanced encryption standard AES algorithm into message authentication code algorithm in RSSP-?,and the FPGA design and implementation of MASL-AES-MAC algorithm based on AES.The safety of the improved protocol is verified by the formal analysis modeling tool Casper/FDR,moreover,the joint simulation experiment of Quartus-? and Modelsim shows that the improved algorithm has better real-time performance and improves the safety information transmission performance of CTCS-3 Train Control System.