1. A method implemented on a computer for producing an automaton capable of providing an access control decision upon receiving an access control request, the method comprising: accepting by the computer of context based access control policies specified in a formal descriptive language, wherein the context based access control policies are policies granting/denying access based on dynamic events; processing by the computer of the context based access control policies specified in the formal descriptive language, wherein the processing of the context based access control policies includes converting the context based access control policies to monadic second order formulas including events and variables; and, converting by the computer of the monadic second order formulas to the automaton.