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While pull-based peer-to-peer (P2P) live streaming prevails in recent years, an important but less studied problem is security. To achieve security, confidentiality of the streaming data is essential and the corresponding key management scheme must scale well without degrading the system performance too much. In this paper, we thus propose P2P-SMP -a novel secure multicast protocol specifically designed for pull-based P2P live streaming -to achieve good reliability in key distribution and guarantee that the decryption key is received by legitimate peers before the corresponding encrypted streaming data even in dynamic P2P environments. Through extending the pull-based P2P live streaming protocol to distribute rekeying messages and further adopting a batch rekeying method, P2P-SMP dramatically reduces the communication and computing overhead in key distribution. The efficiency and reliability of P2P-SMP is evaluated through extensive simulations.

IPTV is highly advocated in recent years. Today, the growth of the residential users makes it possible to broadcast live video content through global internet to a great population of end users. In this paper, we mainly describe the design and deployment experiences of a peer-to-peer (P2P) based IPTV system called Gridmedia since P2P is universally recognized as a scalable and cost-effective means for group communication. In order to reduce the playback latency at end users as well as offer resilience to high churn rate in peer community, Gridmedia organizes end users into an unstructured overlay while proposes an efficient push-pull streaming mechanism to distribute video segments among partner nodes. To further verify the prototype, on one hand we conduct extensive experiments over PlanetLab to confirm the overlay architecture and streaming mechanism in Gridmedia can greatly reduce the average playback latency as compared to previous works; on the other hand the practical deployment of Gridmedia system over global Internet also demonstrated it could reliably support large number of users without need of network infrastructure. We also discuss, in a practical way, the issues when perfecting a prototype to a publicly released platform and system performance during live broadcasting CCTV Spring Festival Gala 2006.

The goal of Digital Rights Management (DRM) technology is to distribute digital contents in a secure manner that can protect and manage the rights for all participants in contents distribution value-chain including producers, providers, distributors, and consumers. In most existing DRM schemes, rights are granted per content to a consumer, and all the right-granting information including consumer identifier, content identifier, content decryption key and usage rules are tightly related and stored in the license. However, these schemes cause the problems that the license management will become complicated in proportion to increasing the number of contents or consumers, especially in large-scale content distribution scenarios. In this paper, we propose an efficient Right-granting Model with Hierarchical Group Rights (RMHGR) which can grant rights on some group of contents to a group of consumers. Furthermore, we propose a corresponding DRM system model which differs from previous DRM systems in terms of packaging mechanism, license structure, and content decryption key generation method. A comparison with other DRM schemes has shown that our proposed scheme is low overhead, scalable, and efficient for large-scale content distribution.

In this paper, we emphasize salient experiences on peer to peer based live video streaming. First, we describe a two-layer overlay structure and a multi-sender based transmission algorithm to broadcast video programs. Although both numerical analysis and practical data reveal feasibility to support nearly 600 concurrent users in 500kbps streaming delivery, the tremendous workload imposed upon structure maintenance server limits its scalability. Therefore, in the second implementation, a gossip-based overlay protocol is deployed to provide distributed membership management, and an efficient scheduling mechanism is proposed to fetch video contents with lower delay. The experimental data from PlanetLab indicates that it ensures continuous playback, demanding bandwidth and low latency. More interestingly, the maximum concurrent users 15,239 with one common streaming server in 300kbps distribution sessions was tracked in Feb. 2005, which demonstrates that it offers a scalable and reliable streaming system for a large and highly dynamic population of end hosts.

The increasing popularity of distributed and collaborative applications prompts the need for secure communication in collaborative groups. Some distributed collaborative key management protocols have been proposed to provide group communication privacy and data confidentiality for collaborative groups. However, most of them rekey on each member change, and the costs of group rekeying can be quite substantial for large groups with frequent membership changes. In this paper, we propose a scalable distributed key management scheme using a distributed one-way function tree named SIKAS which can significantly reduce the computation and communication costs of maintaining the group key based upon period-based group rekeying. A comparison with previous work has shown that SIKAS provides scalability and rekeying efficiency while preserving both distributed and collaborative properties.

Recently, overlay networks have been proposed to address the problem of scalability in providing video-on-demand (VoD) service. However, from the perspective of service providing, their efficiency has not been carefully studied and still remains far from clear, especially considering the impacts of user interactivities and in the case of multiple files with different and varying popularities on sharing. Towards this end, in this paper, by analyzing more than 20,000,000 real workload traces, we first identify two practical factors which we believe have determinant impacts on the scalability: user interactivities and popularity differences among files. Then we further evaluate cache-and-relay (CR), a representative scheme of overlay networks, with the real workload traces. Simulation results show that CR only save about half of the server bandwidth even when there is no buffer constraint at clients, not so scalable as our original expectation.

We present a novel single source peer-to-peer multicast architecture called GridMedia which mainly consists of 1) multi-sender based overlay multicast protocol (MSOMP) and 2) multi-sender based redundancy-retransmitting algorithm (MSRRA). The MSOMP deploys mesh-based two-layer structure and groups all the peers into clusters with multiple distinct paths from the source root to each peer. To address the problem of long burst packet loss, the MSRRA is proposed at the sender peers to patch the lost packets by using receiver peer loss pattern prediction. Consequently, GridMedia provides a scalable and reliable video streaming system for a large and highly dynamic population of end hosts, and ensures the quality of service in terms of continuous playback, bandwidth demanding and low latency. A real experimental system based on GridMedia architecture has been constructed over CERNET and broadcasting TV programs for seven months. More than 140,000 end users have been attracted with almost 600 simultaneously being online at Aug 2004 during Athens Olympic Games

In this paper, we describe the design and implementation of a peer-to-peer based live video streaming system called Gridmedia. Gridmedia organizes the nodes into an unstructured overlay, and adopts a novel push-pull streaming mechanism to fetch data from the partner nodes. The pull mode in the unstructured overlay can work well with the high churn rate in P2P environment while the push mode can efficiently reduce the accumulated latency at user side. We also depict our practical solution of traversal over network address translators (NATs) and firewalls. Gridmedia was adopted by CCTV to broadcast the CCTV Spring Festival Gala 2005 through Internet and attracted more than 500,000 users all over the world during that night, with the maximum amount of concurrent users reaches as high as 15,239

In most existing digital rights management scheme, rights are granted per content to a consumer, and all the right-granting information including consumer identifier, content identifier, content decryption key and usage rules are tightly related and stored in the license. However, these schemes cause the problems that the license management becomes complicated in proportion to increasing the number of contents or consumers, especially in large-scale content distribution scenarios. In this paper, we propose a scalable digital rights management framework which differs from previous DRM systems in terms of packaging mechanism, right-granting method and license structure, and content decryption key generation method. A comparison with other DRM schemes has shown that our proposed scheme is low overhead, scalable, and efficient for large-scale content distribution.