Abstract: Methods, devices and systems for providing content providers with a secure way to multicast their data flows only to legitimate end users. By making a specific decision for each potentially legitimate end user requesting a specific data flow, differing subscriber profiles may be taken into account. Furthermore, end to end encryption is avoided by having a switch and/or router control the specific data flow to a specific end user. Each end user sends a request DTU to the switch and/or router asking for permission to join a multicast group. The switch and/or router extracts identification data from the request data transmission unit (DTU) and determines whether the requesting end user is cleared for the requested specific data flow. This determination may be made by sending a query DTU containing the identification data to a policy server which checks the identification data against preprogrammed criteria in its databases.