This paper introduces an advanced implementation of the Paxos consensus algorithm in which proposals have different priority levels so that higher priority proposals preempt lower priority ones to reduce latency. The operation of the protocol is modeled using preemptive priority queues, which allows us to evaluate system performance in a number of different scenarios. Our results indicate that the implementation of the Paxos algorithm in this manner offers tunable differentiation of completion times, making it suitable for a variety of applications, including permissioned blockchains in IoT scenarios.

74

Paxos is a well-known protocol for state machine replication and consensus in face of crash faults. However, it suffers from inefficiencies in request handling, particularly in scenarios where requests have different inherent priorities. To address this, we propose a priority-aware extension with priority upgrading similar to MultiPaxos, evaluate its performance using a queueing model, and show the improvement in performance metrics such as mean completion and waiting times. Our results demonstrate that integrating prioritization and priority upgrading mechanisms into Paxos reduces latency for high priority requests while ensuring fairness for lower priority ones. The aging-based priority upgrading approach maintains correctness of the consensus process while adding flexibility in managing time-sensitive distributed applications such as permissioned blockchains.

Paxos is a well known protocol for state machine replication and consensus in face of crash faults. However, it suffers from inefficiencies in request handling, particularly in scenarios requiring preemptive prioritization. To address this, we propose a priority-aware extension similar to MultiPaxos and evaluate its performance using a queuing model, and show the improvement in performance metrics such as mean completion and waiting times. Our results demonstrate that integrating prioritization mechanisms into Paxos reduces latency for high-priority requests while ensuring fairness. The aging-based approach maintains correctness of the consensus process while adding flexibility to manage time-sensitive distributed applications such as permissioned blockchains.

Practical Byzantine Fault Tolerance (PBFT) is widely used despite its limitations. In this paper we extend a previously described multiple entry version of PBFT with fast cycle capability. In this approach, multiple data blocks are proposed by different nodes or replicas, but instead of choosing only one to undergo the consensus procedure, replicas collect and order the proposals which are then accepted through a simplified consensus cycle. We analyze the operation of this scheme using a probabilistic model and show that consensus performance actually improves over that of the original PBFT as the traffic load increases. In this manner, the proposed scheme appears to be well suited for blockchain-based Internet of Things (IoT) applications.

This paper reviews the evolution of a powerful class of physical attacks against integrated circuits (ICs), developed initially for performing failure analysis (FA) from the IC backside. Over the last two decades, several publications have demonstrated the effectiveness of these techniques in bypassing the IC protection schemes and extracting the stored assets inside secure ICs. In this work, we take a fresh look at such hardware attacks from three different perspectives. First, we will discuss the potential threat of the attacks against modern technologies and demystify a set of wrong beliefs about the attacks' complexity. Second, we review some technical challenges of such attacks from a law enforcement agency's perspective for unraveling crimes and preventing further crimes by criminals involved. Finally, we give an insight into the future development of FA tools and the opportunities for designing effective countermeasures against attacks through the chip backside.