Abstract This paper proposes a formal method, based on Circus , for developing software systems that respect a joint specification of functionality and confidentiality attributes. We extend the semantics of Circus to capture the information that users can infer about a system’s behaviour, enabling confidentiality and functionality attributes of a system to be specified together. We represent inconsistencies between functionality and confidentiality properties as miracles, rendering insecure functionality infeasible. We present techniques for verifying that a system design’s functionality and confidentiality attributes are mutually consistent, and for ensuring that consistency is maintained by refinement steps.

Hand-sketching is a particularly attractive solution to providing an intuitive design interface for modeling. The goal is to reduce the data collected from the input strokes and to construct a curve that faithfully represents the sketched data. This paper presents a new approach to interactive realtime handsketching in two or three dimensions and is-based on the new approach to general spline datafitting presented in [10,8,9].The goal of our approach is to obtain approximating curves with reasonable accuracy at real-time interactive speeds, and at the same time significantly reduce in the number of coefficients for the curve representation over the original data representation. The approach taken here to obtain realtime interaction is to reduce the data incrementally using new local algorithms while the data is still being sketched.