def start_mining(block_queue, transaction_queue, public_key, private_key):
blockchain = BlockChain([args.ip_other])
miner = Miner(blockchain, public_key)
miner_status = False # Checks if miner is ready to send
# Variables for double-spending attack:
start_attack = False
announced_attack = False
cease_attacks = False
unsent_bad_tx = False
sent_tx = False
ignore_transactions = []
private_fork = []
skip_mine_count = 0
trigger_block = 3
trigger_block_hash = ""
mine_private_blocks = False
private_last_hash = ""
original_blocks = []
while True:
blockchain.resolve()
if args.attacker and start_attack:
# Make sure new blocks don't include the bad_tx from attacker
merkletree, ledger = miner.create_merkle(
transaction_queue, tx_to_ignore=ignore_transactions)
else: # Not attacker or is an attacker and not attacking
merkletree, ledger = miner.create_merkle(transaction_queue)
if not cease_attacks:
if args.attacker:
# 'and sent_tx' ensures attacker only attacks at least one block after bad_tx is sent
start_attack = len(
blockchain.cleaned_keys) > trigger_block and sent_tx
else:
start_attack = len(blockchain.cleaned_keys) > trigger_block
# Send a bad transaction after trigger_block number of blocks in chain
unsent_bad_tx = len(blockchain.cleaned_keys) == trigger_block
# This if statement should only be True once
# Send transaction with intent to double spend
if args.attacker and unsent_bad_tx:
bad_tx = Transaction(public_key, SigningKey.generate().get_verifying_key(), 50,
"give me the goods", sender_pk=private_key).to_json().encode()
print("Sending transaction with intent to double-spend...")
print("Transaction sent.")
ignore_transactions.append(bad_tx)
unsent_bad_tx = False
sent_tx = True
while True:
miner_status = False
# This if statement should only be True once
# Start of attack
if not announced_attack and args.attacker and start_attack:
# Take the hash of the block before the bad_tx
trigger_block_hash = blockchain.cleaned_keys[trigger_block-1]
private_last_hash = trigger_block_hash
# Used to track which blocks to ignore in trying to build new longest chain
original_blocks = copy.deepcopy(
blockchain.cleaned_keys[trigger_block:])
print("=============\nSTART ATTACK!\n============")
announced_attack = True
# Generate new public key and empty out balance from old public key
new_private_key = create_key()
new_public_key = new_private_key.get_verifying_key()
try:
print(
"Double-spending: Making transaction to empty out old account...")
empty_old_account = Transaction(public_key, new_public_key, amount=ledger.get_balance(
public_key), comment="transferring all money out", sender_pk=private_key)
print("sent transaction")
except AssertionError:
# Old account already empty
pass
public_key = new_public_key
private_key = new_private_key
# Take on a new identity
miner = Miner(blockchain, new_public_key)
# Need to create merkle again so coinbase goes to new_public_key
merkletree, ledger = miner.create_merkle(
transaction_queue, tx_to_ignore=ignore_transactions)
# If attack starts, slow down honest miner
if not args.attacker and start_attack:
if skip_mine_count % 500 == 0:
miner_status = miner.mine(merkletree, ledger)
# Keep range of skip_mine_count within (0,500]
skip_mine_count = 0
skip_mine_count += 1
elif args.attacker and start_attack:
# Start mining from block before bad_tx
miner_status = miner.mine_from_old_block(
merkletree, ledger, private_last_hash)
else:
# Mine normally if no attack
miner_status = miner.mine(merkletree, ledger)
mine_or_recv = ""
# Check if mine is successful
if miner_status:
mine_or_recv = "Block MINED "
if args.attacker and start_attack:
# sending_block might not be last block of blockchain
sending_block = find_private_block(
blockchain.chain, private_last_hash, original_blocks)
sending_block_header_hash = binascii.hexlify(
sending_block.header_hash()).decode()
mine_or_recv += sending_block_header_hash
private_fork.append(sending_block)
# Update private_last_hash
private_last_hash = sending_block_header_hash
if len(private_fork) == 3:
for block in private_fork:
block_data = pickle.dumps(block, protocol=2)
send_failed = True
while send_failed:
try:
requests.post("http://"+args.ip_other +
"/block", data=block_data)
send_failed = False
except:
time.sleep(0.1)
private_fork = []
if not check_block_in_chain(blockchain, original_blocks[0]):
print("=============\nATTACK ENDED\n============")
# stop attack
start_attack = False
cease_attacks = True
else:
print(
"Block to void:", original_blocks[0], "Chain:", blockchain.cleaned_keys)
print(
"Block we want to void is still in chain! Continuing attack...")
else: # args.attacker and not start_attack or not args.attacker
sending_block = blockchain.last_block()
mine_or_recv += binascii.hexlify(
sending_block.header_hash()).decode()
data = pickle.dumps(sending_block, protocol=2)
send_failed = True
while send_failed:
try:
requests.post("http://" + args.ip_other +
"/block", data=data)
send_failed = False
except:
time.sleep(0.2)
break
if miner.nonce % 1000 == 0:
# Check if new blocks have been detected
block_queue_status_initial = block_queue.empty()
while not block_queue.empty():
mine_or_recv += "Block RECEIVED "
# If detected, add new block to blockchain
new_block = block_queue.get()
miner.network_block(new_block)
mine_or_recv += binascii.hexlify(
new_block.header_hash()).decode() + " "
if not block_queue_status_initial:
break
block_queue_status_initial = True
print(color(args.color) + "PORT: {}\n".format(args.port) + mine_or_recv +
str(miner.blockchain).split("~~~")[1])
if start_attack and args.attacker:
print(color(args.color) + "private fork:"+" "*14*(trigger_block-2), trigger_block_hash[:10]+" -> ",
[binascii.hexlify(private_block.header_hash()).decode()[:10] for private_block in private_fork])
