Selective security for TLS

Today´s computing environments are becoming increasingly heterogeneous, mostly due to the growth of mobile computing. In this environment, application layer proxies that can adapt and tailor the content to the client´s needs and capabilities as well as to the available network resources are highly beneficial. The problem is that content adaptation proxies are generally incompatible with the notion of end-to-end security. The only generic solution to this problem is the concept of selective security. The idea is to apply security selectively only to the sensitive elements of a data stream and expose the rest to any intermediary system for potential content adaptation. None of the currently used security protocols provides an API for fine-grained control of the application of security mechanisms to a data stream. We propose a simple extension to the transport layer security protocol (TLS), which provides the application with an interface for selectively protecting elements within a data stream. We also discuss a generic application scenario that shows how the proposed extended features can be used in conjunction with content adaptation proxies.