The Security Picalculus and Non - interference ( Extended Abstract )

The security π-calculus is a typed version of the asynchronous π-calculus in which the types, in addition to constraining the input/output behaviour of processes, have security levels associated with them. This enables us to introduce a range of typing disciplines which allow input or output behaviour, or both, to be bounded above or below by a given security level. We define typed versions ofmay andmust equivalences for the security π-calculus, where the tests are parameterised relative to a security level. We provide alternative characterisations of these equivalences in terms of actions in context ; these describe the actions a process may perform, assuming the observer is constrained by a given typing environment. Using these alternative characterisations we prove non-interference results with respect tomay andmust testing. These show that information flow between security levels can be controlled using our typing systems.