Anonymous Management of Trust Relationships in Decentralized P2P Systems



Decentralized Peer-to-Peer (P2P) offer both opportunities and threats. Most of the P2P networks operational today are voluntary file sharing applications. However, because of its open and decentralized nature, it has been very susceptible to malicious users sharing harmful content like viruses, trojans or probably just wasting valuable resources of the network. In order to use P2P networks in a more useful setting, it is extremely important to provide security and to prevent unwanted elements from participating.

One way to minimize threats in P2P networks is to use community-based reputations as trust measurements. The use of such trust ratings in one form or another is fast becoming a de-facto standard. The idea is to dynamically assign each peer a trust rating based on its performance in the overlay network and store it at a suitable place. Any peer wishing to interact with another peer can make an informed decision based on such a rating.

An important challenge in managing such trust relationships is to design a protocol to secure the placement and access of these trust ratings. In a decentralized scenario, this has to be done by the peers themselves. This opens a host of interesting issues. One of the issues is the reluctance of peers to be a trust store for another peer in the network, since that attracts malicious behavior from its competitors (if the peer performs well) or from the peer itself (if it doesnt want the community to know of its poor performance). Another issue is the fear of retaliation, preventing peers from giving negative ratings (the issue that is troubling eBay).

We try to solve this problem through the use of mutual anonymity. If nobody knows who the trust store is (including the peer whose trust value is being stored), there is hardly a chance that the trust store will be attacked. Similary, we also provide a right to secret ballot to peers providing ratings for peers. We provide a complete protocol using Public Key Cryptography mechanisms to provide a fair and honest mechanism. There are various challenging issues that need to handled e.g. how to select good trust stores, how to access ratings from them without knowing who/where they are? TrustMe provides all the answers.



Aameek Singh
Ling Liu



Aameek Singh, Ling Liu, "TrustMe: Anonymous Management of Trust Relationships in Decentralized P2P Systems", Proceedings of the third IEEE International Conference on P2P Computing, Linkping, Sweden, Sept, 2003. |Slides|


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Aameek Singh <aameek[AT]>



This work is partially supported by the National Science Foundation under a CNS Grant, an ITR grant, a Research Infrastructure grant, and a DoE SciDAC grant, an IBM SUR grant, an IBM faculty award, and an HP equipment grant. Any opinions, findings, and conclusions or recommend ations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or DoE.


2007 Aameek Singh