Design and implementation of a query processor for a trusted distributed data base management system

Distributed systems are vital for the efficient processing required in military and commercial applications. For many of these applications, it is especially important that the distributed data base management systems (DDBMS) operate in a secure manner. For example, the DDBMS should allow users, who are cleared at different security levels access to the data base at different levels of data sensitivity without compromising security. A DDBMS with multilevel user/datahandling capability is called a trusted distributed data base management system (TDDBMS). This article focuses on query processing in a TDDBMS. It describes the security issues, algorithms for query processing, and design and implementation of a query processor prototype for a TDDBMS.