Believing the Integrity of a System

An integrity policy defines the situations when modification of information is authorised and is enforced by the protection mechanisms of a system. Traditional models of protection tend to define integrity in terms of ad-hoc authorisation techniques whose effectiveness are justified more on the basis of experience and "best practice" rather than on any theoretical foundation. In a complex application system it is possible that an integrity policy may have been incorrectly configured, or that the protection mechanisms are inadequate, resulting in an unexpected system compromise. This paper examines the meaning of integrity and and describes a simple belief logic approach for analysing the integrity of a system configuration.