1. An authorization engine for enforcing a group-centric secure authorization policy, the authorization engine comprising: a processor accessible by a user and configured to execute instructions; a memory containing an access-limited object and further containing executable instructions configured to instruct the processor to execute a stateful security policy, including the operations: define a group; receive a join command wherein the user joins the group as a member; receive a leave command wherein the user leaves the group; receive an add command wherein the object is added to the group as to be in the group; receive a remove command wherein the object is removed from the group; and authorize the user to access the object only if the user is a member of the group and the object is in the group; and wherein the stateful security policy is based on and authorization equivalent to a stateless security policy.