Evidence processing and privacy issues in evidence-based reputation systems

Issues related to processing of evidence in evidence-based reputation systems, with a particular concern for user privacy, are discussed in our paper. The novel idea of evidence-based reputation (or trust) systems is that such systems do not rely on an objective knowledge of user identity. One has instead to consider possible privacy infringements based on the use of data (evidence) about the previous behaviour of entities in the systems. We provide a brief introduction to evidence-based trust/reputation systems, as well as to the privacy issues, addressing the common problem of many papers that narrow the considerations of privacy to anonymity only. We elaborate on the concept of pseudonymity through aspects of evidence storing and processing. This, together with a consideration of current work on trust models, leads to our specification of requirements for the trust model for evidence-based systems supporting pseudonymity.