Threat Adaptive Byzantine Fault Tolerant State-Machine Replication

Abstract

Critical infrastructures have to withstand advanced and persistent threats, which can be addressed using Byzantine fault tolerant state-machine replication (BFT-SMR). In practice, unattended cyberdefense systems rely on threat level detectors that synchronously inform them of changing threat levels. However, to have a BFT-SMR protocol operate unattended, the stateof-the-art is still to configure them to withstand the highest possible number of faulty replicas f they might encounter, which limits their performance, or to make the strong assumption that a trusted external reconfiguration service is available, which introduces a single point of failure. In this work, we present ThreatAdaptive the first BFT-SMR protocol that is automatically strengthened or optimized by its replicas in reaction to threat level changes. We first determine under which conditions replicas can safely reconfigure a BFT-SMR system, i.e., adapt the number of replicas n and the fault threshold f , so as to outpace an adversary. Since replicas typically communicate with each other using an asynchronous network they cannot rely on consensus to decide how the system should be reconfigured. ThreatAdaptive avoids this pitfall by proactively preparing the reconfiguration that may be triggered by an increasing threat when it optimizes its performance. Our evaluation shows that ThreatAdaptive can meet the latency and throughput of BFT baselines configured statically for a particular level of threat, and adapt 30% faster than previous methods, which make stronger assumptions to provide safety.

System on Chip Rejuvenation in the Wake of Persistent Attacks

“…The default rejuvenation frequency µ ∈ [0, T ] is random, in order to obfuscate the pattern from the adversary. The rejuvenation protocol is inspired from software rejuvenation in [42], [43]. However, we envision possible optimizations in such a hardware-based setting, that we plan to address in the future.…”

A Fault‐tolerant model for tuple space coordination in distributed environments

“…The tool tests the error in BFT algorithms by introducing randomly generated network and process faults during the protocol execution runtime. Silva et al 45 proposed a threat adaptive Byzantine fault tolerant state‐machine replication protocol to enable replicas to enhance their utilization of system resources and raise their resilience threshold. In Reference 19, the tuple space model has been duplicated among hosts to perform faster coordination in the smart home system (SHS).…”