Abstract
One of the most important responsibilities of a database management system (DBMS) is maintaining the integrity of data. Traditional database integrity mechanisms have evolved in DBMSs to fulfill this need, including transaction management to maintain consistent results when requests execute concurrently and explicitly asserted integrity constraints to limit the values deemed legal. DBMSs also provide access controls that limit who is permitted to modify data. Despite these controls, however, DBMSs are still vulnerable to integrity violations due to users modifying data in unexpected ways or abusing their access authorizations for fraudulent or malicious purposes. Recent work in generalized integrity models, such as the Clark-Wilson model [Clark 1987, Clark 1988] and separation of duty models [Sandhu 1988, Badger 1989], provides new approaches for addressing these additional integrity needs. This paper interprets the Clark-Wilson model in the context of a DBMS, in general, and of a trusted relational DBMS, in particular. It presents a layered policy for Clark-Wilson integrity and dynamic separation of duty, that can augment the conventional database integrity capabilities of a commercial trusted DBMS and can coexist with its existing policies. Building on existing models, our dynamic separation of duty model defines a general control structure and dynamic authorization capabilities. Clark-Wilson integrity and separation of duty are realized in the policy as interpreted in terms of DBMS objects and their interrelationships.
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