Privacy-Protecting Algorithms for Digraph Shortest Path Queries

Trust relation in this work refers to permission that is given to a user at a source-host to access another user at a target-host through an authentication key with a unique fingerprint. The database owner can form a directed graph out of these trust relations, such that user-host pairs are considered nodes and fingerprints as arrows. The authors of this article present a novel protocol to query the shortest path from node A to node B, in a privacy preserving manner. The authors would like to use a cloud to perform such queries, but they do not allow the cloud to learn any information about the graph, nor the query. Also, the database owner is prevented from learning any information about the query, except that it happened.