PBFT Implementation

Building

# Build executables
go build -o bin/node.exe cmd/node/main.go
go build -o bin/testclient.exe cmd/testclient/main.go
go build -o bin/keygen.exe cmd/keygen/main.go

Running

# 1. Generate keys (only do this once)
bash scripts/generate_keys.sh

# 2. Start all nodes (in one terminal)
bash scripts/run_nodes.sh

# 3. Run test client (in another terminal)
bash scripts/run_csv_test.sh testcases/test_input.csv

# Or manually:
./bin/testclient.exe testcases/test_input.csv

Starting Nodes Manually

If you want more control, start each node in separate terminals:

./bin/node.exe n1 50051
./bin/node.exe n2 50052
./bin/node.exe n3 50053
./bin/node.exe n4 50054
./bin/node.exe n5 50055
./bin/node.exe n6 50056
./bin/node.exe n7 50057

Then run test client:

./bin/testclient.exe testcases/test_input.csv

Interactive Commands

After each test set:

• log <nodeID> - view node's log
• db <nodeID> - view node's datastore
• status <seq> <nodeID> - view status of sequence at node
• view <nodeID> - view all view changes at node
• allstatus <seq> - view status at all nodes
• next - continue to next test

Config

• 7 replicas (n1-n7), f=2
• 10 clients (A-J), each starts with 10 units
• View change timeout: 5 seconds
• Client timeout: 8 seconds per retry

How it Works

Normal Operation

1. Client sends request to primary
2. Primary broadcasts PRE-PREPARE (assigns sequence number)
3. Backups send PREPARE to primary
4. Primary broadcasts PREPARE_COLLECTOR (contains 2f prepares)
5. All nodes send COMMIT to primary
6. Primary broadcasts COMMIT_COLLECTOR (contains 2f+1 commits)
7. All nodes execute and reply to client

View Changes

• Timer-based detection when primary fails
• Exponential backoff on repeated failures
• NEW-VIEW messages include prepared requests from old view

Byzantine Attacks

• crash - node stops participating
• sign - corrupt message signatures
• dark(targets) - drop messages to specific nodes
• time - delay messages
• equivocation(targets) - send conflicting messages to different nodes

Project Structure

cmd/
  node/main.go           - node entry point
  testclient/main.go     - test client
  keygen/main.go         - key generation
pkg/
  pbft/                  - core protocol implementation
  client/                - client logic
  byzantine/             - byzantine attack behaviors
  crypto/                - ed25519 signatures
  storage/               - state persistence and datastore
  util/                  - config and logging
proto/
  pbft.proto             - protobuf definitions
scripts/
  generate_keys.sh       - generate ed25519 keys for all nodes/clients
  run_nodes.sh           - start all nodes
  run_csv_test.sh        - run test with csv file
  cleanup.sh             - clean temp files
testcases/
  test_input.csv         - test cases
  test_input2.csv        - more test cases

Bonus Features

✨ Optimistic Phase Reduction (Implemented)

This project includes an Optimistic Phase Reduction bonus feature that improves performance by skipping the commit phase when all replicas are responsive.

Key Features:

• Fast Path: Skips commit phase when all 3f+1 prepares received within timeout
• Automatic Fallback: Reverts to normal 3-phase protocol on timeout or Byzantine behavior
• Performance: 50% reduction in messages, 25% reduction in latency (in ideal conditions)
• Configurable: Enable/disable via pkg/util/config.go

Test it:

./bin/testclient.exe testcases/test_optimistic.csv

See OPTIMISTIC_PHASE_REDUCTION.md for complete documentation.

📊 Checkpointing (Implemented)

The system includes a checkpointing mechanism for garbage collection and state recovery.

Notes

• Nodes log to tmp/logs/
• State saved in tmp/state/
• Keys in tmp/keys/
• Run bash scripts/cleanup.sh to clear temp files