In this paper, we present Novasky, a real-world Video-on-Demand (VoD) system capable of delivering cinematicquality video streams to end users. The foundation of the Novasky design is a peer-to-peer (P2P) storage cloud, storing and refreshing media streams in a decentralized fashion using local storage spaces of end users. We present our design objectives in Novasky, and how these objectives are achieved using a collection of unique mechanisms, with respect to caching strategies, coding mechanisms, and the maintenance of the supplydemand relationship when it comes to media availability in the P2P storage cloud. The production Novasky system has been implemented with over 100,000 lines of code. It has been deployed in the Tsinghua University campus network, operational since September 2009, attracting 10,000 users to date, and providing over 1,000 cinematic-quality video streams with bit rates of 1-2 Mbps. Based on real-world traces collected over 6 months, we show that Novasky can achieve rapid startups within 4-9 seconds, and extremely short seek latencies within 3 seconds. Our empirical experiences with Novasky may bring valuable insights to future designs of production-quality P2P storage cloud systems.
The security issue is becoming more and more prominent since user’s private information being outsourced to the somewhat untrustworthy cloud. Encrypting the information before uploading them to the cloud is one of ultimate solutions. Secure searchable encryption schemes and secure ranking schemes have been proposed to help retrieving the most relevant documents over the cloud. However the present methods are encumbered by the huge computing and communicating occupation of the cipher text. In this paper, a fully homomorphic encryption based secure ranked search model over the hybrid cloud is proposed. By introducing hybrid cloud, which typically composed by private cloud and public cloud, the high cost of computing and communicating of the cipher text is transferred to the trustworthy private cloud, in which the decrypting are performed. The client does not need to perform any heavy computations, thence making the secure ranking practical from the client’s point of view.
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