“Randomized Intrusion-Tolerant Asynchronous Services”
Master’s thesis, Mestrado em Informática, Departamento de Informática, Faculdade de Ciências da Universidade de Lisboa, Dec. 2006
Abstract: Randomized agreement protocols have been around for more than two decades. Often assumed to be inefficient due to their high expected communication and time complexities, they have remained largely overlooked by the community-at-large as a valid solution for the deployment of fault tolerant distributed systems. This thesis aims to demonstrate that randomization can be a very competitive approach even in hostile environments where arbitrary faults can occur. The implementation of a stack of randomized intrusion-tolerant protocols is described, and its performance evaluated under different fault loads. The stack provides a set of relevant services ranging from basic communication primitives up to atomic broadcast. The protocols share a set of important structural properties, namely they tolerate arbitrary faults, have an optimal resilience, are time-free, completely decentralized, and signature-free. The experimental evaluation shows that the protocols are efficient and no performance reduction is observed under certain Byzantine faults.
Research line(s): Fault and Intrusion Tolerance in Open Distributed Systems (FIT)