Formal BFT Trace Verification for Byzantine Node Detection

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Solution Overview

Problem

Existing Byzantine Fault Tolerant (BFT) consensus algorithms lack a systematic approach for detecting and identifying Byzantine actors, which can undermine the consensus process, and existing solutions require specific hardware or adapted algorithms, limiting their applicability and effectiveness.

Innovation Solution

A model-based method that complements BFT consensus algorithms with an individual accountability process, using formal behavioral models to analyze trustworthy trace logs and identify Byzantine actors through a multi-trace analysis, allowing for the detection of multiple Byzantine actors and providing evidence of their behavior without requiring modifications to the consensus algorithm or specific hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If BFT consensus algorithms are used to ensure consensus despite Byzantine actors, then system reliability is improved, but the ability to detect and identify Byzantine actors deteriorates

Engineering Contradiction:
Improveconsensus reliabilityVSAvoidByzantine actor detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces a formal behavioral model as an intermediary between the BFT consensus algorithm and the trace logs. This model serves as a mediator that systematically compares expected node behaviors against actual observed behaviors, enabling the detection of Byzantine actors without modifying the core consensus algorithm. The model acts as a reference framework that highlights deviations and identifies malicious nodes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces manual or ad-hoc analysis methods with an automated offline runtime verification algorithm. This algorithm systematically processes multi-trace log files and formal behavioral models to automatically detect Byzantine actors, substituting mechanical manual inspection with computational verification that provides consistent and reliable detection capabilities.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Difficulty of detecting and measuring

If existing accountability solutions are implemented to identify Byzantine actors, then detection capability is improved, but device complexity and hardware requirements worsen

Engineering Contradiction:
ImproveByzantine actor detectionVSAvoidhardware requirements
Core Design Contradiction:
Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent creates formal behavioral models that are simplified copies or abstractions of the actual consensus algorithm behavior. These models capture the essential expected behaviors of nodes without requiring the full complexity of the actual system implementation. By analyzing these model copies against trace logs, the system achieves detection capability without needing complex hardware modifications to the original system.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent extracts the detection functionality from the core consensus algorithm by using offline runtime verification. The formal behavioral model and verification algorithm are separated from the live consensus process, allowing Byzantine detection to be performed on recorded trace logs without adding complexity or hardware requirements to the running consensus system.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of operation

If Proof of Work consensus is used to achieve fair leader selection, then consensus fairness is improved, but energy consumption increases

Engineering Contradiction:
Improveleader selection fairnessVSAvoidenergy consumption
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent enables the transition from Proof of Work to Proof of Stake consensus mechanisms by providing reliable Byzantine actor detection capabilities. This parameter change in the consensus mechanism allows the system to maintain fairness and security through stake-based leader selection rather than energy-intensive computational puzzles, significantly reducing energy consumption while preserving consensus integrity through the formal verification approach.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4443810B1System, method and computer program product for detecting byzantine nodes in a consensus-based distributed system
Publication Date: 2025.09.10 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP4443810B1 patent drawingFigure 1
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AI summary

A computer implemented method for detecting Byzantine nodes in a consensus-based distributed system is disclosed. The distributed system is composed of a plurality of nodes wherein agreement between nodes are reached by a Byzantine Fault Tolerant (BFT) consensus algorithm, each node being defined by at least a local distributed registry configured to collect in a local trace log file all inputs and outputs of local transactions occurring at the respective node during an execution of the distributed system. The method comprises the steps of: - receiving a multi-trace log file comprising all local trace log files collected during an execution period of the distributed system; - executing an offline runtime verification algorithm on the multi-trace log file with a formal behavioral model, the formal behavioral model being a representation of the BFT consensus algorithm in a formal language, and being composed of a plurality of local models, each local model defining at least a local behavioral specification representing an expected behavior of one node of the plurality of nodes of the distributed system. The runtime verification algorithm comprises when a deviation from an expected behavior is detected, the steps of: - replacing a local model generating the detected deviation by a local Byzantine model, wherein the local Byzantine model allowing the detected deviation to occur; -pursing the execution of the runtime verification algorithm; and -repeating the replacing and pursing steps until the whole multi-trace log file is analyzed. The method allows creating a list of all local models replaced by a local Byzantine model during the execution of the runtime verification algorithm, the list thereby identifying the corresponding nodes of the distributed system as being Byzantine nodes.