A data processing system has a browser with scripting engine means for executing a script. The scripting engine means implements a public scripting engine and a private scripting engine. The browser is configured to have the script executed by the public scripting engine if the script does not require access to a pre-determined resource at the system. The browser is configured to have the script executed by the private scripting engine if the script requires access to the pre-determined resource. Only the private scripting engine has an interface for enabling the script to access the predetermined resource. The scripting engine means is configured to prevent the private scripting engine from communicating data to the public scripting engine or to a non-approved server external to the data processing system.