The purpose of the MSEC WG is to standardize protocols for securing group communication over internets, and in particular over the global Internet. Initial efforts will focus on scalable solutions for groups with a single source and a very large number of recipients. Additional emphasis will be put on groups where the data is transmitted via IP-layer multicast routing protocols (with or without guaranteed reliability). The developed standard will assume that each group has a single trusted entity (the Group Controller) that sets the security policy and controls the group membership. The standard will strive to provide at least the following basic security guarantees: + Only legitimate group members will have access to current group communication. This includes groups with highly dynamic membership. + Legitimate group members will be able to authenticate the source and contents of the group communication. This includes cases where group members do not trust each other. An additional goal of the standard will be to protect against denial-of-service attacks, whenever possible. Due to the large number of one-to-many multicast applications and the sometimes conflicting requirements these applications exhibit, it is believed that a single protocol will be unable to meet the requirements of all applications. Therefore, the WG will first specify a general Reference Framework that includes a number of functional building blocks. Each such building block will be instantiated by one or more protocols that will be interchanable. The Reference Framework will not only describe one-to-many multicast, but also many-to-many multicast. In addition, as a secondary goal the MSEC WG will also focus on distributed architectures for group key management and group policy management, where for scalability purposes multiple trusted entities (such as Key Distributors) are deployed in a distributed fashion. For this purpose, the Reference Framework will not only describe one-to-many multicast, but also many-to-many multicast. MSEC will generate at least the following documents, which could be considered as base documents: 1. An RFC describing the security requirements of multicast security and an RFC describing the MSEC Architecture. 2. An RFC describing the Group Key Management Architecture and an RFC describing Group Policy Management Architecture in MSEC. 3. Several RFCs describing specifications for protocols that implement source authentication, group key management and group policy management. As multicast security covers a broad range of issues, and therefore touches other Working Groups in the IETF, the MSEC WG will work closely with othersecurity-related Working Groups (e.g. IPsec, IPSP), as well as other Working Groups which maybe considered a 'consumer' of the technologies produced in the MSEC WG (e.g. AVT, MMUSIC) or which may have a multicast focus (e.g. PIM, RMT, IDRM, MAGMA). With this in mind, the MSEC WG is open to receiving new work items, whenever it is considered appropriate to be homed in the MSEC WG. Such drafts will be matured in conjunction with the MSEC base documents.