An authorization model for workflows named WAM that is capable of specifying authorizations in such a way that subjects gain access to requred objects only during the excution of the task.

The Goal : to  synchronize the authorization flow with the workflow.

The Approach: associate an Authorization Template with each task, which allows appropriate authorizations to be granted only when the task starts and to revoke them when the task finishes.

The implementation: A model of implementation based on Petri nets.

Tools : A Petri net reprentation for conducting safety analysis since the safety problem in the authorization model is equivalent to the reachability problem in Petri nets.