The spreading of multicast technology enables the development of group communication and so dealing with digital streams becomes more and more common over the Internet. Given the flourishing of security threats, the distribution of streamed data must be equipped with sufficient security guarantees. To this aim, some architectures have been proposed, to supply the distribution of the stream with guarantees of, e.g., authenticity, integrity, and confidentiality of the digital contents. This paper shows a formal capability of capturing some features of secure multicast protocols. In particular, both the modeling and the analysis of some case studies are shown, starting from basic schemes for signing digital streams, passing through proto- cols dealing with packet loss and time-synchronization requirements, concluding with a secure distribution of a secret key. A process-algebraic framework will be exploited, equipped with schemata for analysing security properties and compositional principles for evaluating if a property is satisfied over a system with more than two components
