Many incentive mechanisms have been proposed to foster cooperation among nodes in Peer-To-Peer (P2P) networks. Unfortunately, most of existing solutions rely on the existence of an online centralized authority that is in charge of a fair distribution and transaction of credits (incentives) between peers. Such centralized mechanisms mainly suffer from privacy leakage and single point of failure problems. To cope with these problems, the authors propose to take advantage of the distributed nature of P2P networks in order for the peers to take care of credit-based operations. Cheating and other DoS attacks are prevented thanks to a threshold security mechanism where the operation should be approved by a predefined certain number of peers.