Design And Implementation Of Security Instant Messaging System Based On TCP/IP Protocol

With the further development of network communication technology and computer technology, Instant Messaging has been a requirement of on-line activities. This project design and implementation the new security instant messaging based on the topic of the existing network communication technology, database technology and information security technology.The new security instant messaging system design the data encryption algorithm and key transmission and management mechanisms, based on the original instant messaging system, which guarantee the instant of the data communication and the safety of the communication process and storage of information, provided a more convenient and quicker, secure office communication platform for Internal staff of enterprises.This system is designed by object-oriented and modular design method, which used computer technologies based on network communication technology, database technology, DLL technology, Multi-threading technology, software reuse and so on, this system has functions of the text communication, file transfer, users groups, users and log management, transaction management and so on, and has features of instant and safety.This system uses composite structure of three-tier C/S and P2P communi- cation model to design system architecture, uses overlapped I/O model to implementation server's parallel processing, uses ADO interface to access to SQL Server database to design data management module, uses encryption algorithm based on Feistel structure to implementation data transmission and storage, and design the safety of key transmission and key management mechanism combination of features of the system.