Ponce, Victor

Due to the dynamic nature of P2P systems, it is impossible to keep an accurate
history of the transactions that take place while avoiding security attacks
such as whitewashing and collusion, and abuse such as freeriding . This is why it
is important to develop a mechanism that rewards cooperative peers and punishes
misbehaving peers. Modeling P2P networks as social structures can allow incentive
mechanisms to be used that prevent the negative behaviors mentioned. In this thesis,
we extend a social network algorithm to include credit transfer between peers in
order to reduce the path length of queries. We also develop a selection strategy that
involves different aspects of peer interactions in P2P networks, which is promoted by
our credit transfer mechanism that discourages misbehaving peers by taking away
credits that they have with good peers and transferring them to more cooperative
ones. The simulation results show that our algorithm is effective in reducing the
debt between peers, meaning that peers become more cooperative, and shortening
the average path length to a satisfied query while increasing delivery ratio.