Biblio

Since the number of processors and cores on a single chip is increasing, the interconnection among them becomes significant. Network-on-Chip (NoC) has direct access to all resources and information within a System-on-Chip (SoC), rendering it appealing to attackers. Malicious attacks targeting NoC are a major cause of performance depletion and they can cause arbitrary behavior of links or routers, that is, Byzantine faults. Byzantine faults have been thoroughly investigated in the context of Distributed systems however not in Very Large Scale Integration (VLSI) systems. Hence, in this paper we propose a novel fault model followed by the design and implementation of lightweight algorithms, based on Software Defined Network-on-Chip (SDNoC) architecture. The proposed algorithms can be used to build highly available NoCs and can tolerate Byzantine faults. Additionally, a set of different scenarios has been simulated and the results demonstrate that by using the proposed algorithms the packet loss decreases between 65% and 76% under Transpose traffic, 67% and 77% under BitReverse and 55% and 66% under Uniform traffic.

The performance, dependability, and security of cloud service systems are vital for the ongoing operation, control, and support. Thus, controlled improvement in service requires a comprehensive analysis and systematic identification of the fundamental underlying constituents of cloud using a rigorous discipline. In this paper, we introduce a framework which helps identifying areas for potential cloud service enhancements. A cloud service cannot be completed if there is a failure in any of its underlying resources. In addition, resources are kept offline for scheduled maintenance. We use redundant resources to mitigate the impact of failures/maintenance for ensuring performance and dependability; which helps enhancing security as well. For example, at least 4 replicas are required to defend the intrusion of a single instance or a single malicious attack/fault as defined by Byzantine Fault Tolerance (BFT). Data centers with high performance, dependability, and security are outsourced to the cloud computing environment with greater flexibility of cost of owing the computing infrastructure. In this paper, we analyze the effectiveness of redundant resource usage in terms of dependability metric and cost of service deployment based on the priority of service requests. The trade-off among dependability, cost, and security under different redundancy schemes are characterized through the comprehensive analytical models.

The surprising success of cryptocurrencies has led to a surge of interest in deploying large scale, highly robust, Byzantine fault tolerant (BFT) protocols for mission-critical applications, such as financial transactions. Although the conventional wisdom is to build atop a (weakly) synchronous protocol such as PBFT (or a variation thereof), such protocols rely critically on network timing assumptions, and only guarantee liveness when the network behaves as expected. We argue these protocols are ill-suited for this deployment scenario. We present an alternative, HoneyBadgerBFT, the first practical asynchronous BFT protocol, which guarantees liveness without making any timing assumptions. We base our solution on a novel atomic broadcast protocol that achieves optimal asymptotic efficiency. We present an implementation and experimental results to show our system can achieve throughput of tens of thousands of transactions per second, and scales to over a hundred nodes on a wide area network. We even conduct BFT experiments over Tor, without needing to tune any parameters. Unlike the alternatives, HoneyBadgerBFT simply does not care about the underlying network.