Secure Key Exchange Against Man-in-the-Middle Attack: Modified Diffie-Hellman Protocol

Abstract

Abstract : One of the most famous key exchange protocols is Diffie-Hellman Protocol (DHP) which is a widely used technique on which key exchange systems around the world depend. This protocol is simple and uncomplicated, and its robustness is based on the Discrete Logarithm Problem (DLP). Despite this, the protocol is vulnerable to the Man-in-the-Middle (MitM) attack. The scope of this thesis is to provide a relevant review on secure key exchange mechanisms that are employed in practice to deal with the issue of sharing securely the secret key between the authorized partied in symmetric cryptosystems. On the other hand, the practical aspect of this thesis is concerned by the redesign and realization of a modified version of the DHP protocol. The proposal is based on two verification stages to withstand the issue of Man-in-the-Middle (MITM) attack. In the first stage, the pseudo-random value that one of the communicating parties (sender ) sends to the other legitimate party (the receiver) will be verified weither there exists any malicious manipulation on it. In the second stage, the random value that the receiver sends to the sender will be also verified weither there exists any malicious manipulation on it. Mathematical proofs have been carried out to demonstrate the effectiveness of our contribution and its robustness against Man-in-the-Middle (MitM) attack.