The Research And Implementation Of Strategies On Secure Peer-to-Peer Instant Messaging

Instant Messaging(IM) has already been adopted widely in Internet so far. Recently, the application of Peer-to-Peer(P2P) technology to IM has further impelled its development. However, along with the quickness and convenience of the service offered by IM, it also brings many security threats. In the latest years, the attack against IM becomes more and more often. Though achievements to decrease the burden of IM server via P2P technology and to guarantee the security of IM have been made in recent research and application, many problems remain to be solved.Therefore, the thesis analyses the application of P2P technology in IM, proposes the effective P2P IM strategy, analyses the major security threats encountered by IM, designs corresponding strategy to guarantee IM security, and finally realize these strategies. The main work of this paper is as follows: Firstly, on the basis of the thorough research and analysis of application of P2P in IM, the paper puts forward the P2P IM system architecture based on lightweight Medi-Server, and correlative P2P IM strategy, to support reliable P2P IM. Secondly, the paper proposes the strategy to dissolve the threats confronting IM in the security of connection, data exchange, store of configuration information and messaging record, that is, to apply the PKI mechanism to IM, utilize the SSL technology and that of USB Key, use methods such as encryption, decryption, signature and verification of signature to secure the connection and data exchange of the P2P IM, protect the configuration information and messaging record, and use digital envelope technology to support safe and efficient group IM communication.Thirdly, according to features of the threats from worms, the paper researches into the method to construct a set of effective strategies to precaution the attacks from worms and curb the transmission of them, by means of the mechanism of digital signature, CAPTCHA validation and IM messages flux monitoring.Lastly, the paper designs and realizes SP2PIM: a P2P IM model system, in which the concerning strategies in the paper can be realized. Then, the paper teststhe system and assesses it through comparison with some popular IM products, so as to verify the applicability, efficiency, and practicality of these strategies.