The lack of available identity information in attribute-based trust management systems complicates the design of the audit and incident response systems, anomaly detection algorithms, collusion detection/prevention mechanisms, and reputation systems taken for granted in traditional distributed systems. In this paper, we show that as two entities in an attribute-based trust management system interact, each learns one of a limited number of
describing their communication partner. We show that these virtual fingerprints can be disclosed to other entities in the open system without divulging any attribute or absolute-identity information, thereby forming an opaque pseudo-identity that can be used as the basis for the above-mentioned types of services. We explore the use of virtual fingerprints as the basis of Xiphos, a system that allows reputation establishment without requiring explicit knowledge of entities’ civil identities. We discuss the trade-off between privacy and trust, examine the impacts of several attacks on the Xiphos system, and discuss the performance of Xiphos in a simulated grid computing system.