Krisztian Gado - A Game Theoretic Analysis of TOR's Resilience to Entry-Exit and End-to-End Attacks

Tor is among the most used networks for anonymous communication. This anonymity can be undermined via entry-exit and end-to-end attacks. Using Game Theory, we introduce and analyze the viability of several methods for reducing Tor’s vulnerability to such attacks. Entry-exit attacks rely upon controlling entry and exit nodes within the Tor Network, while end-to-end attacks utilize Autonomous Systems. Because both types of attacks rely on chance, we consider the success probability maximizing strategies of adversaries. We analyze changes to Tor’s routing strategy that decrease the success probability of such attacks. Our goal is to support anonymity preserving systems against large Autonomous Systems providers and attackers with access to large computing power. We build upon previous work by eliminating exit node bandwidth quotas within Tor and decreasing asymmetric routing to make compromising anonymity less likely. We show the probability that anonymity is preserved if one uses Tor for a year can be increased from ~62% to ~85% if our suggestions are implemented. Krisztian Gado is a researcher at Lewis and Clark College.