Secure search in enterprise webs: tradeoffs in efficient implementation for document level security

• Authors: Peter Bailey;David Hawking;Brett Matson
• Venue: CIKM '06 Proceedings of the 15th ACM international conference on Information and knowledge management
• Year: 2006

Document level security (DLS) -- enforcing permissions prevailing at the time of search -- is specified as a mandatory requirement in many enterprise search applications. Unfortunately, depending upon implementation details and values of key parameters, DLS may come at a high price in increased query processing time, leading to an unacceptably slow search experience. In this paper we present a model and a method for carrying out secure search in the presence of DLS within enterprise webs. We report on two alternative commercial DLS search implementations. Using a 10,000 document experimental DLS environment, we graph the dependence of query processing time on result set size and visibility density for different classes of user. Scaled up to collections of tens of thousands of documents, our results suggest that query times will be unacceptable if exact counts of matching documents are required and also for users who can view only a small proportion of documents. We show that the time to conduct access checks is dramatically increased if requests must be sent off-server, even on a local network, and discuss methods for reducing the cost of security checks. We conclude that enterprises can effectively reduce DLS overheads by organizing documents in such a way that most access checking can be at collection rather than document level, by forgoing accurate match counts, by using caching, batching or hierarchical methods to cut costs of DLS checking and, if applicable, by using a single portal both to access and search documents.