Authentication and authorization are the two crucial functions of any modern security and access control mechanisms. Authorization for controlling access to resources is a dynamic characteristic of a workflow system which is based on true business dynamics and access policies. Allowing or denying a user to gain access to a resource is the cornerstone for successful implementation of security and controlling paradigms. Role based and attribute based access control are the existing mechanisms widely used. As per these schemes, any user with given role or attribute respectively is granted applicable privileges to access a resource. There is third approach known as predicate based access control which is less explored. We intend to throw light on this as it provides more fine-grained control over resources besides being able to complement with existing approaches. In this paper we proposed a predicate-based access control mechanism that caters to the needs of cloud-based workflow systems
