Chaum’s Protocol for Detecting Man-in-the-middle: Explanation and Discussion

Title of thesis: CHAUM’S PROTOCOL FOR DETECTING MAN-IN-THE-MIDDLE: EXPLANATION AND DISCUSSION William Newton, Master of Computer Science, 2010 Thesis directed by: Dr. Alan T. Sherman Department of Computer Science In this research paper, I explain David Chaum’s patent that describes the Man-In-The-Middle (MITM) detection protocol. The MITM Detection Protocol (MDP) uses three stages to entrap an adversary that reveals her existence based on contextual information from each scenario. One of the primary goals of this research is to develop a detailed understanding of Chaum’s novel concept since the language describing the MDP presented a clouded explanation. My second goal is to re-describe the protocol using conventional notation and illustrations for two cases in each scenario, with and without an adversary. The explicit illustrations provided within this paper clearly define the exchange between two communicants and their ability to detect an adversary. I define the assumptions based around the common random string model that eliminates prior exchange of information and distribution of shared secrets. A discussion follows the explanation of the protocol which concludes that Chaum’s MDP adds technical value and merit towards achieving a MITM detection mechanism based on a restrictive assumption set; however, the elevated complexity experienced by the user contributed to the lack of integration and acceptance of the MDP onto existing hardware solutions.