Detect and Handle Equivocation Attacks - The Consensus

                      TASK
                    

Implementation

Simulate a Byzantine node that sends contradictory messages to different peers (equivocation). Show that PBFT correctly handles this.

Request:  {"type": "simulate_equivocation", "msg_id": 1, "byzantine_node": "n2", "sequence": 1, "messages_sent": {
    "to_n1": {"prepare": {"value": "A"}},
    "to_n3": {"prepare": {"value": "B"}},
    "to_n4": {"prepare": {"value": "A"}}
}}
Response: {"type": "simulate_equivocation_ok", "in_reply_to": 1, "equivocation_detected": true, "evidence": {"node": "n2", "conflicting_values": ["A", "B"]}, "consensus_safe": true, "chosen_value": "A", "reason": "majority_agreed_on_A"}

Request:  {"type": "equivocation_report", "msg_id": 2}
Response: {"type": "equivocation_report_ok", "in_reply_to": 2, "byzantine_nodes_detected": ["n2"], "total_equivocations": 1}

Sample Test Cases

Equivocation is detectedTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1","n2","n3","n4"]}}
{"src":"c1","dest":"n1","body":{"type":"simulate_equivocation","msg_id":2,"byzantine_node":"n2","sequence":1,"messages_sent":{"to_n1":{"prepare":{"value":"A"}},"to_n3":{"prepare":{"value":"B"}},"to_n4":{"prepare":{"value":"A"}}}}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}

Equivocation report lists Byzantine nodesTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1","n2","n3","n4"]}}
{"src":"c1","dest":"n1","body":{"type":"simulate_equivocation","msg_id":2,"byzantine_node":"n2","sequence":1,"messages_sent":{"to_n1":{"prepare":{"value":"X"}},"to_n3":{"prepare":{"value":"Y"}},"to_n4":{"prepare":{"value":"X"}}}}}
{"src":"c1","dest":"n1","body":{"type":"equivocation_report","msg_id":3}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}

Hints

Hint 1▾

Equivocation: a Byzantine node sends different messages to different peers

Hint 2▾

Detection: peers compare received messages and find contradictions

Hint 3▾

Evidence: two signed messages from the same node with different values for the same sequence

Hint 4▾

PBFT handles this because 2f+1 matching messages are required for commit

Hint 5▾

The contradictory node is effectively ignored when it cannot produce enough matching messages

Resources

Equivocation and BFT

How equivocation attacks work and how BFT protocols defend against them

                      OVERVIEW
                    

Theoretical Hub

Concept overview coming soon

Key Concepts

equivocationcontradictory messagesevidence collectionByzantine detection

main.py

python