Biblio

Data storage in Distributed Storage Systems (DSS) is a multidimensional optimization problem. Using network coding, one wants to provide reliability, scalability, security, reduced storage overhead, reduced bandwidth for repair and minimal disk I/O in such systems. Advances in the construction of optimal Fractional Repetition (FR) codes, a smart replication of encoded packets on n nodes which also provides optimized disk I/O and where a node failure can be repaired by contacting some specific set of nodes in the system, is in high demand. An attempt towards the construction of universally good FR codes using three different approaches is addressed in this work. In this paper, we present that the code constructed using the partial regular graph for heterogeneous DSS, where the number of packets on each node is different, is universally good. Further, we also encounter the list of parameters for which the ring construction and the T-construction results in universally good codes. In addition, we evaluate the FR code constructions meeting the minimum distance bound.

Minimum-Storage Regenerating (MSR) codes have emerged as a viable alternative to Reed-Solomon (RS) codes as they minimize the repair bandwidth while they are still optimal in terms of reliability and storage overhead. Although several MSR constructions exist, so far they have not been practically implemented mainly due to the big number of I/O operations. In this paper, we analyze high-rate MDS codes that are simultaneously optimized in terms of storage, reliability, I/O operations, and repair-bandwidth for single and multiple failures of the systematic nodes. The codes were recently introduced in [1] without any specific name. Due to the resemblance between the hashtag sign \# and the procedure of the code construction, we call them in this paper HashTag Erasure Codes (HTECs). HTECs provide the lowest data-read and data-transfer, and thus the lowest repair time for an arbitrary sub-packetization level α, where α ≤ r⌈k/r⌉, among all existing MDS codes for distributed storage including MSR codes. The repair process is linear and highly parallel. Additionally, we show that HTECs are the first high-rate MDS codes that reduce the repair bandwidth for more than one failure. Practical implementations of HTECs in Hadoop release 3.0.0-alpha2 demonstrate their great potentials.

Now-a-days Internet has become mostly content centric. Named Data Network (NDN) has emerged as a promising candidate to cope with the use of today's Internet. Several NDN features such as in-network caching, easier data forwarding, etc. in the routing method bring potential advantages over conventional networks. Despite the advantages, there are many challenges in NDN which are yet to be addressed. In this paper, we address two of such challenges in NDN routing: (1) Huge storage overhead in NDN router (2) High communication over-heads in the network during propagation of routing information updates. We propose changes in existing NDN routing with the aim to provide a low-overhead solution to these problems. Here instead of storing the Link State Data Base (LSDB) in all the routers, it is kept in selected special nodes only. The use of special nodes lowers down the overall storage and update overheads. We also provide supporting algorithms for data forwarding and update for grid network. The performance of the proposed method is evaluated in terms of storage and communication overheads. The results show the overheads are reduced by almost one third as compared to the existing routing method in NDN.

In this paper, we focus on versatile and scalable key management for Advanced Metering Infrastructure (AMI) in Smart Grid (SG). We show that a recently proposed key graph based scheme for AMI systems (VerSAMI) suffers from efficiency flaws in its broadcast key management protocol. Then, we propose a new key management scheme (iVerSAMI) by modifying VerSAMI's key graph structure and proposing a new broadcast key update process. We analyze security and performance of the proposed broadcast key management in details to show that iVerSAMI is secure and efficient in terms of storage and communication overheads.

In Smart Grids (SGs), data aggregation process is essential in terms of limiting packet size, data transmission amount and data storage requirements. This paper presents a novel Domingo-Ferrer additive privacy based Secure Data Aggregation (SDA) scheme for Fog Computing based SGs (FCSG). The proposed protocol achieves end-to-end confidentiality while ensuring low communication and storage overhead. Data aggregation is performed at fog layer to reduce the amount of data to be processed and stored at cloud servers. As a result, the proposed protocol achieves better response time and less computational overhead compared to existing solutions. Moreover, due to hierarchical architecture of FCSG and additive homomorphic encryption consumer privacy is protected from third parties. Theoretical analysis evaluates the effects of packet size and number of packets on transmission overhead and the amount of data stored in cloud server. In parallel with the theoretical analysis, our performance evaluation results show that there is a significant improvement in terms of data transmission and storage efficiency. Moreover, security analysis proves that the proposed scheme successfully ensures the privacy of collected data.

The goal of this work is to design cache coherence protocols with many cores that can be verified with state-of-the-art automated verification methodologies. In particular, we focus on flat (non-hierarchical) coherence protocols, and we use a mostly-automated methodology based on parametric verification (PV). We propose several design guidelines that architects should follow if they want to design protocols that can be parametrically verified. We experimentally evaluate performance, storage overhead, and scalability of a protocol verified with PV compared to a highly optimized protocol that cannot be verified with PV.