A computer security architecture applies selected rules from among a set of rules defining one or more security policies to a given set of security context parameters to produce security verdicts, each representing whether a certain action requested by a subject entity is permissible. Each security policy is associated with a corresponding communication interface. A plurality of gateway engines are each associated with at least one of the subject entities and dedicated to interfacing with the security server. Each of the gateway engines carries out monitoring of requested actions by the associated subject entity and, for each requested action, identifies a security context. A security policy is determined for the requested action based on a corresponding security context, and a security verdict is obtained via a communication interface corresponding to the applicable security policy.