Mimir: Term-distributed indexing and search for secret documents

Abstract

In order to access sensitive documents shared over government, army and enterprise intranets, users rely on an indexing facility where they can quickly locate relevant documents they are allowed to access, (1) without leaking information about the remaining documents, (2) without imposing large load on the receptionist, and (3) with a balanced load on the index servers. To address this problem, we propose Mimir, a distributed cipher retrieval system for sensitive documents. Mimir constructs the distributed indexes based on load balanced term distribution for better search efficiency and load balanced query. Mimir utilizes encryption with random key, partial key update, and access control based on role and user to protect sensitive data and improve query efficiency. Mimir uses dynamic pipelined search strategy to balance the load of the management server and reduce the search delay. Our experiments show that Mimir can effectively protect secret data and answer queries nearly as fast as an ordinary inverted index.