This paper describes a security model we refer to as the Probabilistic Multi-Lateral Security Model (PMLSM). The P-MLSM is designed to analyze security issues in Ubiquitous Multimedia Services, envisioned to be flexible digital systems built upon the global broadband network. There is interest on a broad range of security issues concerning such services. A comprehensive, flexible and reliable model that addresses these issues is greatly needed.

The P-MLSM considers security as a multi-lateral mutual measure between different objectives, perspectives and knowledge concerning the system. We will then describe a probabilistic nature of the PMLSM. Lastly, via an example, we will illustrate how various security related phenomena and design criteria can be analyzed using the model.