Self-stabilizing Byzantine- and Intrusion-tolerant Consensus

TL;DR

This paper introduces the first self-stabilizing Byzantine- and intrusion-tolerant multivalued consensus algorithm for asynchronous message-passing systems, enhancing fault tolerance with automatic recovery capabilities.

Contribution

It extends the previous MR solution by incorporating self-stabilization, enabling recovery from arbitrary transient faults in addition to Byzantine and communication failures.

Findings

First self-stabilizing solution for intrusion-tolerant multivalued consensus.

Handles arbitrary transient faults alongside Byzantine failures.

Operates in asynchronous message-passing systems with optimal resilience.

Abstract

One of the most celebrated problems of fault-tolerant distributed computing is the consensus problem. It was shown to abstract a myriad of problems in which processes have to agree on a single value. Consensus applications include fundamental services for the environments of the Cloud or Blockchain. In such challenging environments, malicious behavior is often modeled as adversarial Byzantine faults. At OPODIS 2010, Moste}faoui and Raynal, in short, MR, presented a Byzantine- and intrusion-tolerant solution to consensus in which the decided value cannot be a value proposed only by Byzantine processes. In addition to this validity property, MR has optimal resilience since it can deal with up to t < n/3 Byzantine processes, where n is the number of processes. We note that MR provides this multivalued consensus object (which accepts proposals taken from a set with a finite number of values) assuming the availability of a single Binary consensus object (which accepts proposals taken from the set {0,1}). This work, which focuses on multivalued consensus, aims at the design of an even more robust solution than MR. Our proposal expands MR's fault-model with self-stabilization, a vigorous notion of fault-tolerance. In addition to tolerating Byzantine and communication failures, self-stabilizing systems can automatically recover after the occurrence of arbitrary transient-faults. These faults represent any violation of the assumptions according to which the system was designed to operate (provided that the algorithm code remains intact). To the best of our knowledge, we propose the first self-stabilizing solution for intrusion-tolerant multivalued consensus for asynchronous message-passing systems prone to Byzantine failures.