Many large content publishers use multiple content distribution networks to deliver their content, and many commercial systems have become available to help a broader set of content publishers to benefit from using multiple distribution networks, which we refer to as content multihoming. In this paper, we conduct the first systematic study on optimizing content multihoming, by introducing novel algorithms to optimize both performance and cost for content multihoming. In particular, we design a novel, efficient algorithm to compute assignments of content objects to content distribution networks for content publishers, considering both cost and performance. We also design a novel, lightweight client adaptation algorithm executing at individual content viewers to achieve scalable, fine-grained, fast online adaptation to optimize the quality of experience (QoE) for individual viewers. We prove the optimality of our optimization algorithms and conduct systematic, extensive evaluations, using real charging data, content viewer demands, and performance data, to demonstrate the effectiveness of our algorithms. We show that our content multihoming algorithms reduce publishing cost by up to 40%. Our client algorithm executing in browsers reduces viewer QoE degradation by 51%.

In secure group communications, users of a group share a common group key. A key server sends the group key to authorized new users as well as performs group rekeying for group users whenever the key changes. In this paper, we investigate scalability issues of reliable group rekeying, and provide a performance analysis of our group key management system (called keygem) based upon the use of key trees. Instead of rekeying after each join or leave, we use periodic batch rekeying to improve scalability and alleviate out-of-sync problems among rekey messages as well as between rekey and data messages. Our analyses show that batch rekeying can achieve large performance gains. We then investigate reliable multicast of rekey messages using proactive FEC. We observe that rekey transport has an eventual reliability and a soft real-time requirement, and that the rekey workload has a sparseness property, that is, each group user only needs to receive a small fraction of the packets that carry a rekey message sent by the key server. We also investigate tradeoffs between server and receiver bandwidth requirements versus group rekey interval, and show how to determine the maximum number of group users a key server can support.

: The Internet of Things is one of the most adapting technology with the applications in multiple domains. Bringing together, huge number of devices and networks to access the information at one platform is called an IoT network. IoT is shifting its security priorities to consider data access control from a data-centric perspective. Recently, Muhammad et.al. has proposed a scheme of two-factor user authentication in WSN and claimed that his scheme is secured against various attacks [1]. However, we have found some pitfalls in his work and based on that, proposed a work, which is an improvement of the earlier works done by M.L. Das on access control policy. In our work, we have modified the existing algorithm by adding new computational load without disturbing the work done in the previous algorithm. The integration of our proposed work with the earlier work makes the whole process more protective from various insider attack. The proposed algorithm "Disjunctive XOR Two Factor Authentication Method " can be implemented with real life applications. The security patches implemented in the proposed algorithm, attempts to fix receptiveness of the gateway and makes the scheme more secured and adaptive. The proposed work is tested in an unsecured wireless sensor network and found to be capable of protecting from various attacks such as Bypass and Insider attacks. With addition, it also gives the flexibility, to allow user to change or update its login password within a secured environment. In our work, we have also proposed, the Mutual Authentication between the Gateway(GY-node) and Sensor Node(Sn) such that it gets protected by an inside attacker and secondly, to allow user to change/update password independently and thirdly proved that the work proposed is secured from insider and Bypass attacker.