PIC MCU-based 802.1x Access Authentication Technology Research

At present,with the Internet,especially the rapid development of campus networks,the traditional broadband access authentication methods(such as:PPPOE) increasingly expose their various defects.And the Ethernet accessing technology based on the IEEE 802.1x authentication protocol can implement discrete control and centralized authentication. Most of the current broadband access embedded devices use the traditional broadband access authentication,so the embedded devices based on the 802.1x authentication protocol need to be researched and developed.This paper is arranged as follow:At the beginning,this thesis analyzes the characteristics of the traditional authentication for accessing broadband network and those of 802.1x authentication protocol in detail, then,it researches the authentication principle and mechanism of 802.1x protocol.After that,the.thesis studies the 4 times handshaking process of the 802.1x protocol with the Ethereal protocol analyzer.The design of the hardware system adopts PIC18F2455 MCU(Micro-Controller Unit) as the master controller,with ENC28J60 being employed as the hardware system' s Ethernet controller.In this chapter,peripheral circuits connected to ENC28J60 are studied in detail,such as the reset circuit,timer oscillator,LED configuration,input and output level,and so on.In the last part of the hardware design,the SPI(Serial Peripheral Interface) protocol for the connection between PIC18F2455 and ENC28J60 is researched heavily,relevant source code of SPI communication being provided.In the relevant chapters about software design for the system,this thesis analyzes the structure of each interactive packet,and the meaning of each field in the relevant packets. The thesis also designs the flow chart of the 4-times handshaking,and researches how to implement each packet in a PIC single-chip.We know that in the third handshaking of 802.1x protocol,the authentication system adopts the mechanism of encrypting request based on MD5.Considering the complexity of MD5 and the limited resources in a single-chip computer,this thesis optimizes the implementation of the algorithm,such as memory arrangement and "zero-copy",etc.The experiment shows that the system is stable,the authentication is reliable,and the process of authentication is safe.The design of hardware and software for this system provides client support and source code level data for further studies of the authentication based on 802.1x.Thus,it has important reference value.