Employing Trusted Computing for the forward pricing of pseudonyms in   reputation systems
  Reputation and recommendation systems are fundamental for the formation of community market places. Yet, they are easy targets for attacks which disturb a market's equilibrium and are often based on cheap pseudonyms used to submit ratings. We present a method to price ratings using trusted computing, based on pseudonymous tickets. 
Nicolai Kuntze, Dominique Maehler, and Andreas U. Schmidt