With the advent of an increasing number of multicast services such as audio/video streaming and news broadcast, accounting for the resources consumed by subscribers becomes essential. However, multicast environ­ments are inherently more susceptible to attacks. Although e-commerce protocols such as SSL, TLS, and SET protocols offer some forms of security, they cannot be directly applied to secure e-commerce sessions in the multi­cast environment. As secured multicast services gain popularity in the Internet, at one point there would be a significant response from the service providers to support e-commerce through multicast networks. Therefore, this book presents a Multicast Security Protection Profile (MSPP) that identifies and secures the operating environment of multicast sessions. An architectural framework called SETMS has been designed to secure e-commerce trans­actions for multicast services. It provides authentication of host through HIP, authorization of subscriber and his e-payments through a variant of the 2KP, accounting for the subscriber's resource consumption, and supports non-repudiation through PKI. SETMS has been evaluated using the CC based MSPP specs and validated using the AVISPA. The book is addressed to professionals and researchers involved in securing computer networks; multicast and e-commerce environments, and the e-commerce protocol designers.