Separation of duties for access control enforcement in workflow environments

Separation of duty, as a security principle, has as its primary objective the prevention of fraud and errors. This objective is achieved by disseminating the tasks and associated privileges for a specific business process among multiple users. This principle is demonstrated in the traditional example of separation of duty found in the requirement of two signatures on a check. Previous work on separation of duty requirements often explored implementations based on role-based access control (RBAC) principles. These implementations are concerned with constraining the associations between RBAC components, namely users, roles, and permissions. Enforcement of the separation of duty requirements, although an integrity requirement, thus relies on an access control service that is sensitive to the separation of duty requirements. A distinction between separation of duty requirements that can be enforced in administrative environments, namely static separation of duty, and requirements that can only be enforced in a run-time environment, namely dynamic separation of duty, is required. It is argued that RBAC does not support the complex work processes often associated with separation of duty requirements, particularly with dynamic separation of duty. The workflow environment, being primarily concerned with the facilitation of complex work processes, provides a context in which the specification of separation of duty requirements can be studied. This paper presents the “conflicting entities” administration paradigm for the specification of static and dynamic separation of duty requirements in the workflow environment.