Research And Analysis On Deniable Authentication Protocols

Network is playing a more and more important role in people’s daily life. Many network-based activities, such as online trade, computer games, internet communication and remote education have been developing regularly. For this very reason, the security of online activities is being paid more and more attention to. Authentication is one of the most important aspects of information technology, while deniable authentication is one special case of authentication.Deniable authentication protocols are such protocols that the intended receiver can identify the source of the message, but the intended receiver cannot prove it to any third party.The intended receiver "cannot prove it to any third party" means that the receiver himself can compute all the communicating parameters sent between him and the sender, using his own private key and the messages he got from the sender. Even he reveals the message, no third party would identify whether what he reveals is really from the sender or forged by the receiver himself. The receiver can’t persuade the third party to believe him either. So even if a malicious third party confirms the revealed message with the sender, the sender can deny it and indicate that the message is forged by the receiver, which means, the sender can refuse to admit the messages he sent.Deniable authentication is widely used in many online scenarios such as e-commerce, electronic voting, e-auction, online negotiation, remote education etc, since a sender can deny his participation in the communicating process or deny the information he transmitted. It can be used to assure the credibility and integrity of the message, and make the online activities securer and fairer.In this paper, by comparing and analyzing all kinds of deniable authentication protocols, we review the background, the basic theory, the application scenarios and the securities of deniable authentication, analyze the probable leaks, attacks and the improved schemes of the deniable authentication protocols, compare the differences in security and efficiency, design new secure deniable authentication with high efficiency and prove them to have the safety properties.First, we describe the notion, history and application scenarios of deniable authentication in detail introduce the relevant background knowledge. We propose a new standard to classify deniable authentication protocols:strong deniability and weak deniability. We also put different protocols into different classes according to the difficult problems they base on, and point out the common attacks in deniable authentications.Second, we study the deniable authentication protocols based on traditional difficult problems, using the protocols based on Diffie-Hellman difficult problem as an example. By analyzing a famous deniable authentication protocol, we describe the attacks and security of protocols based on traditional difficult problems, and find ways to overcome them. Then we design a new universal encrypted authentication protocol based on generalized ElGamal signature scheme, and prove the completeness, deniability of it. The protocol provides mutual authentication and can resist PIM attacks such as forgery attack and impersonate attack.Finally, we study deniable authentication protocols based on bilinear pairings, give the security model of bilinear protocols and formalized definitions of deniability and unforgeability against adaptive chosen-message attack. We design a new universal encrypted deniable authentication protocol based on bilinear pairings and prove it to be complete, deniable and unforgeable against adaptive chosen-message attack. The protocol also provides mutual authentication and can resist replay attack and PIM attack.