PBFT Implementation (CSE535 Project 2)

This is an implementation of the Practical Byzantine Fault Tolerance (PBFT) consensus protocol for CSE535.

Implementation Details

Core Components

• Linear PBFT consensus protocol implementation using collector same as primary
• Pre-prepare, Prepare, and Commit phases
• View change mechanism
• Basic client-replica communication

Bonus Features Implemented

1. Threshold Signatures

   • Used for signature aggregation in consensus phases like sending collected prepare and collected commit
   • Implemented using BLS signature scheme via Herumi BLS library

2. Checkpointing

   • Periodic state synchronization mechanism
   • State recovery functionality

3. Optimistic Phase Reduction

   • Reduced commit consensus phases in fault-free scenarios i.e. full quorum (3f+1)
   • Fallback to standard PBFT when needed

Project Structure

• client.cpp: Client implementation
• node.cpp: Replica node implementation
• orchestrator.cpp: System orchestrator
• messages.proto: Protocol buffer message definitions
• bls_helper.h: BLS signature utilities
• logger.h: Logging functionality
• threadpool.h: Thread pool implementation
• resettable_timer.h: Timer implementation

Build Instructions

mkdir build
cd build
cmake ..

Running Instructions

cmake --build . --target run_orchestrator # inside build directory

Dependencies

• CMake (>= 3.10)
• gRPC/Protocol Buffers
• BLS Signature Library
• C++17 compiler

References

• ChatGPT : Used chatGPT to discuss design scenarios, optimise data structure usage and to debug code errors.
• https://github.com/herumi/bls : For sample CPP bls usage and structure identification
• Co-pilot : For formatting the readme file.