Expressing Trust in Distributed Systems: the Mismatch Between Tools and Reality1

Distributed systems typically support processes that involve humans separated by space and by organizational boundaries. Because of its ability to enable secure communications between parties that do not share keys a priori, public key cryptography is a natural building block for the elements of these computing systems to establish trust with each other. However, if the trust structure we build into the computing systems does not match the trust structure in the human systems, then this trust infrastructure has not achieved its goal. In this paper, we assess the inability of the standard PKI-based tools to capture many trust situations that really arise in current distributed systems, based on our lab’s experience trying to make these tools fit. We offer some observations for future work that may improve the situation.