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Most prior work on the use of key management algorithms to enable confidentiality of video delivery has been conducted in the context of IP Multicast. In this paper, we consider the unique challenges and opportunities of integrating key management algorithms in an overlay multicast system. We conduct a systematic and extensive performance evaluation of strategies for key dissemination in the context of an operational overlay broadcasting system on the Planetlab testbed using real traces of join/leave dynamics. We show that leveraging TCP in each hop of the overlay dissemination structure can significantly simplify reliable key dissemination. The performance can be further enhanced if convergence properties of overlays are considered. We show that using two specialized dissemination structures, one for data and one for keys, potentially achieves low overhead for key dissemination without sacrificing application performance. To our knowledge, this is the first paper to study key management schemes in an overlay context using real implementation and Internet experiments and the first to consider issues in resilient key dissemination with overlays.