In various Internet applications, reputation systems are typical means to collect experiences users make with each other. We present a reputation system that balances the security and privacy requirements of all users involed. Our system provides
in the form of information theoretic relationship anonymity w.r.t. users and the reputation provider. Furthermore, it preserves
, i.e., all past ratings can influence the current reputation profile of a user. In addition, mutual ratings are forced to be simultaneous and self rating is prevented, which enforces
. What is more, without performing mock interactions —even if all users are colluding— users cannot forge ratings. As far as we know, this is the first protocol proposed that fulfills all these properties simultaneously.