1. A method for deriving current and maximal permissions for executable content using: a. one or more executable content descriptions; b. one or more sets of permissions (access rights) that describe the operations that executable content can perform on objects; c. one or more permission equations that compute a set of permissions from one or more other sets of permissions; d. one or more permission propositions that specify conditions under which associated modifications to permissions apply; e. one or more policy graphs that associate permissions, permission equations, and/or permission propositions with graph nodes; wherein the method for deriving current and maximal permissions comprises the following steps; f. deriving one or more permission equations and one or more permission propositions from policy graphs; g. deriving one or more maximal sets of permissions from policy graphs; h. selecting granted permissions from within an associated maximal set of permissions; i. combining one or more maximal sets of permissions into the maximal permissions using one permission equation and one or more permission propositions; j. combining one or more granted permissions into one current set of permissions which are a subset of the maximal permissions using one permission equation and one or more permission propositions.