  Inspired by the design patterns of object-oriented software architecture, we
offer an initial set of "privacy patterns". Our intent is to describe the most
important ways in which software systems can offer privacy to their
stakeholders. We express our privacy patterns as class diagrams in the UML
(Universal Modelling Language), because this is a commonly-used language for
expressing the high-level architecture of an object-oriented system. In this
initial set of privacy patterns, we sketch how each of Westin's four states of
privacy can be implemented in a software system. In addition to Westin's states
of Solitude, Intimacy, Anonymity, and Reserve, we develop a privacy pattern for
an institutionalised form of Intimacy which we call Confidence.
