The present invention includes a system and method for defending against unwanted observations of the information conveyed by electronic devices. The system allows users to access sensitive information in public without the fear of visual or other observational leaks. The present invention intercepts sensitive data elements before they are conveyed to a user and replaces the sensitive data with non-sensitive information referred to as aliases. In addition, the system provides a means of computing with sensitive data in a non-observable way. All of this is accomplished while maintaining full functionality and legacy compatibility across applications.