Research And Implementation Of Embedded HTTPS Server Based On ARM-Linux

With the development of the technology of computer and micro-electronics, embedded system has been widely used in many fields such as industry control, information home appliances, communication equipments, intelligent instruments. In these fields, many embedded instruments are demanded to link to the Internet so that they can be used to accomplish remote control. The basic way is to set up a HTTP server in embedded instruments so they can be accessed through WWW by using browsers on client computer, yet it will bring an inevitable security problem on Internet. HTTPS (Hypertext Transfer Protocol over Secure Socket Layer), which is based on SSL (Secure Socket Layer), was brought up by Netscape company to provide a secured HTTP transfer, thus it will be an efficient security solution to build a HTTPS server on embedded instruments.This paper achieved some deep research in HTTP protocol and SSL protocol and embedded technology that based on ARM. To begin with, this paper analyzed how to accomplish a secured transfer over HTTPS, which is to add an extra SSL layer between HTTP standard protocol layer and the transfer protocol layers below it in the TCP/IP referential module and then studied the information exchange process of HTTP protocol that based on request/response scheme and the handshake encryption of SSL protocol. This paper designed the integral structure of this system, and used the S3C2410 that base on 32 bytes ARM920T CPU as hardware and Linux as operation system, and OpenSSL as basis of application layer.Secondly, built an basic environment of embedded HTTPS server, and used Vmware virtual machines to install a Linux operation system on the host computer, then build an cross compiling environment following by setting up a serial network services. Then compiled and configured and transformed operation system and root file system into hardware platform based on the transformation of system loading program bootloader.Finally, after intensive study of the relevant theory, this paper designed the server's basic structure and functional parts, in the use of Linux system calls and the OpenSSL API, using C language to implement the embedded HTTPS server based on ARM-Linux. Results of the experiments showed that the implementation of the server accomplished the HTTPS interaction process with client browser, able to correctly resolve the HTTP request issued by the browser, and make different responses to return to the browser static resources or CGI programs processing results based on the request method or different resources requests.