A Security Infrastructure for Mobile Transactional Systems

Abstract

In this paper, we present an infrastructure for providing secure transactional support for mobile databases. Our infrastructure protects against external threats - malicious actions by nodes not authorized to access the data. The major contribution of this paper, however, is to classify and present algorithms to protect against internal security threats. Internal threats are malicious ac-tions by authenticated nodes that misrepresent protocol specific information. We quantify the cost of our security mechanisms in context of Deno: a system that supports object replication in a transactional framework for mobile and weakly-connected environments. Our results show that protecting against internal threats comes at a cost, but the marginal cost for protecting against larger cliques of malicious insiders is low. However, even with all the security mechanisms in place, our system commits updates over 50% faster than systems that depend on the Read-once Write-all commit protocol. Lastly, we present results from a probabilistic version of our algorithm that has several orders of magnitude lower computation cost than the traditional public-key based schemes. (Also cross-referenced as UMIACS-TR-2000-19)