Cheat detection for MMORPG on P2P environments

In this paper, we propose a new method for detecting cheat in P2P-based MMORPG. We suppose a typical P2P-based event delivery architecture where the entire game space is divided into subareas and a responsible node (selected from player terminals) delivers each event happened in the sub-area to player nodes there every predetermined time interval called timeslot. In the proposed method, we introduce multiple monitor nodes (selected from player terminals) which monitor the game state and detect cheat when it happens. In order to allow monitor nodes to track the correct game states for the corresponding subarea, we let monitor nodes and a responsible node retain a random number seed and player nodes send their events not only to responsible node but also monitor nodes so that the monitor nodes and the responsible node can uniquely calculate the latest game state from the previous game state and game events which happened during the current timeslot. Either responsible node, monitor nodes or player nodes can detect cheat by comparing hash values of game state which are retained by those nodes periodically, and role back events happened since the last correct game state. Through experiments in PlanetLab, we show that our method achieves practical performance to detect cheats.