Efficient and secure media delivery
With the increasing power of computers and communication networks, interest has grown in a whole new class of multimedia applications such as media-on-demand, subscription services to live sporting events, and online distributed games. Being both popular and bandwidth-intensive, these applications can impose significant load on both the network and individual servers. As these applications continue to mature, companies are beginning to sell access to high-quality versions of these applications. This makes it necessary to protect the data so that only paying customers have access. One way to accomplish this is to encrypt the data with a group key held only by the set of paying customers. When this set changes, the group key must be changed and distributed in an efficient and secure way.In our work we study solutions to improve the efficiency and security of media delivery. Stream merging is a technique for efficiently delivering popular media using multicast and client buffers. We perform a comprehensive comparison of the recently proposed stream merging solutions to gain a deeper understanding of their complexity and performance trade-offs. We also show how to apply stream merging to the live broadcast with time-shifting model. This is a model where a client can join the broadcast at time t and receive the broadcast of time t - w for some offset parameter w ≥ 0. Finally, we study the problem of efficient and secure group key distribution.