Scalable Multicast Key Distribution

groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a \working draft" or \work in progress." Abstract Multicasting is becoming an increasingly important and desired form of communication on the Internet, not surprisingly because its typical applications include audio-and video conferencing 4]. Providing security services, such as traac conndentiality, for multicast communication is particularly problematic, since it involves securely distributing a group key to each of a group's receivers. Traditionally, the key distribution function has been assigned to a central network entity, or Key Distribution Centre (KDC), but this method does not scale for wide-area multicasting, where group members may be widely-distributed across the internetwork, and a wide-area group may be densely populated. No eeective solution to this problem has been proposed to date. This paper addresses the multicast key distribution problem and provides a scal-able solution.