Kishor S Trivedi | Duke University (original) (raw)

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Papers by Kishor S Trivedi

Cambridge University Press eBooks, Aug 11, 2017

SUMMARY & CONCLUSIONSA Multi-access Edge Computing (MEC) micro data center (MEDC) consists of... more SUMMARY & CONCLUSIONSA Multi-access Edge Computing (MEC) micro data center (MEDC) consists of multiple MEC hosts close to endpoint devices. MEC service is delivered by instantiating a virtualization system (e.g., Virtual Machines or Containers) on a MEC host. MEDC faces more new security risks due to various device connections in an open environment. When more and more IoT/CPS systems are connected to MEDC, it is necessary for MEC service providers to quantitatively analyze any security loss and then make defense-related decision. This paper develops a CTMC model for quantitatively analyzing the security and dependability of a vulnerable MEDC system under lateral movement attacks, from the adversary’s initial successful access until the MEDC becomes resistant to the attack. The proposed model captures the behavior of the system in a scenario where (i) the rate of vulnerable MEC servers being infected increases with the increasing number of infected MEC servers, (ii) each infected MEC server can perform its compromising activity independently and randomly, and (iii) any infected MEC may fail and then cannot provide service. We also introduce the formulas for computing metrics. The proposed model and formula are verified to be approximately accurate by comparing numerical results and simulation results.

John Wiley & Sons, Inc. eBooks, Apr 2, 2003

IEEE Transactions on Reliability, Sep 1, 2021

Mandelbug-caused software failures are significant threats to system availability, especially in ... more Mandelbug-caused software failures are significant threats to system availability, especially in the context of mission-critical and safety-critical systems. However, there is still no systematic method for keeping the software free from Mandelbugs before release. To guarantee the availability of systems suffering from Mandelbugs, environmental-diversity-based fault tolerance techniques have been proposed to recover from the failures caused by them. In this article, we develop and study an analytic model to assess the availability of systems that utilize a sequence of environmental-diversity-based recovery methods. Improving over previous relevant studies, the availability formula we obtain in this article works for any number of recovery methods the system is equipped with; it is also independent on both the nature of those recovery methods and the order of their utilization. In addition, we consider the problem of how to arrange the set of available recovery methods to achieve the largest system availability. Based on the results of our analysis, we develop an open-source tool, called OPENS, which assists in the calculation of the optimal system availability. We validate the effectiveness of the proposed modeling approach in two ways, namely by comparing our results with those obtained for specific systems considered in relevant studies and by conducting numerical analyses for more general scenarios of its application.

Hyperledger Fabric (HLF) is an open-source implementation of a distributed ledger platform for ru... more Hyperledger Fabric (HLF) is an open-source implementation of a distributed ledger platform for running smart contracts in a modular architecture. In this paper, we present a performance model of Hyperledger Fabric v1.0+ using Stochastic Reward Nets (SRN). From our detailed model, we can compute the throughput, utilization and mean queue length at each peer and critical processing stages within a peer. To validate our model, we setup an HLF network in our lab and run workload using Hyperledger Caliper. From our analysis results, we find that time to complete the endorsement process is significantly affected by the number of peers and policies such as AND (). The performance bottleneck of the ordering service and ledger write can be mitigated using a larger block size, albeit with an increase in latency. For the committing peer, the transaction validation check (using Validation System Chaincode (VSCC)) is a time-consuming step, but its performance impact can be easily mitigated since it can be parallelized. However, its performance is critical, since it absorbs the shock of bursty block arrivals. We also analyze various what-if scenarios, such as peers processing transactions in a pipeline, and multiple endorsers per organization.

Cambridge University Press eBooks, Aug 11, 2017

While Blockchain network brings tremendous benefits, there are concerns whether their performance... more While Blockchain network brings tremendous benefits, there are concerns whether their performance would match up with the mainstream IT systems. This paper aims to investigate whether the consensus process using Practical Byzantine Fault Tolerance (PBFT) could be a performance bottleneck for networks with a large number of peers. We model the PBFT consensus process using Stochastic Reward Nets (SRN) to compute the mean time to complete consensus for networks up to 100 peers. We create a blockchain network using IBM Bluemix service, running a production-grade IoT application and use the data to parameterize and validate our models. We also conduct sensitivity analysis over a variety of system parameters and examine the performance of larger networks

Cambridge University Press eBooks, Aug 11, 2017

The uncertainty propagation is to investigate the effect of errors in model input parameters on t... more The uncertainty propagation is to investigate the effect of errors in model input parameters on the system output measure in probability models. In this paper, we present a moment-based approach of the uncertainty propagation of model input parameters. The presented approach requires only the fist two moments of model parameters, and has an advantage in terms of computation over the closed-form, numerical and sampling-based approaches for uncertainty propagation. The paper presents the properties of moment-based approach by comparing the existing Bayes estimation for the uncertainty propagation in a simple reliability model. An availability model of a server with virtual machines is used to illustrate the applicability of our method in practical problems.

Cambridge University Press eBooks, Aug 11, 2017

John Wiley & Sons, Inc. eBooks, Apr 2, 2003

IEEE Transactions on Reliability, Sep 1, 2021

Cambridge University Press eBooks, Aug 11, 2017

on Software Aging and Rejuvenation. His research interests are in reliability, availability, perf... more on Software Aging and Rejuvenation. His research interests are in reliability, availability, performance and survivability of computer and communication systems and in software dependability. His h-index is 97. He works closely with industry in carrying our reliability/availability analysis, providing short courses on reliability, availability, and in the development and dissemination of software packages such as HARP, SHARPE, SREPT and SPNP.

This is a revised version of the popular "bluebook" that is now as a cheaper, paperback.

Reliability and Availability Engineering Modeling, Analysis, and Applications Do you need to know... more Reliability and Availability Engineering Modeling, Analysis, and Applications Do you need to know what technique to use to evaluate the reliability of an engineered system? This self-contained guide provides comprehensive coverage of all the analytical and modeling techniques currently in use, from classical non-state and state space approaches, to newer and more advanced methods such as binary decision diagrams, dynamic fault trees, Bayesian belief networks, stochastic Petri nets, non-homogeneous Markov chains, semi-Markov processes, and phase type expansions. Readers will quickly understand the relative pros and cons of each technique, as well as how to combine different models together to address complex, real-world modeling scenarios. Numerous examples, case studies and problems provided throughout help readers put knowledge into practice, and a solutions manual and Powerpoint slides for instructors accompany the book online. This is the ideal self-study guide for students, researchers and practitioners in engineering and computer science.