def mine_block(self):
if self.hosting_node is None:
return False
last_block = self.__chain[-1]
hashed_block = hash_block(last_block)
# print(hashed_block)
proof = self.proof_of_work()
# Miners should be rewarded for there work.
reward_transaction = Transaction("MINING", self.hosting_node, '',
MINING_REWARD)
# Copy transaction instead of manipulating the orignal
# "open_transactions".
copied_transaction = self.__open_transaction[:]
for tx in copied_transaction:
if not Wallet.verify_transaction(tx):
return False
copied_transaction.append(reward_transaction)
block = Block(len(self.__chain), hashed_block, copied_transaction,
proof)
self.__chain.append(block)
# Resets the open_transaction to an empty list.
self.__open_transaction = []
self.save_data()
return True
def mine_block(self, node):
proof = self.proof_of_work()
# OrderedDict so that the order of the transactions dicrionary will always be the same.
reward_transaction = Transaction('MINING', node, '', self.reward)
# We copy in case our block will be deined, this way we do not override directly our open_transactions.
copied_transactions = self.open_transactions[:]
# Verify block transactions
for tx in copied_transactions:
if not Wallet.verifty_tx_sign(tx):
return False
copied_transactions.append(reward_transaction) # Reward miner transaction
block = Block(len(self.chain), hash_block(self.chain[-1]), copied_transactions, proof)
self.chain.append(block)
self.open_transactions = []
self.save_data()
converted_block = block.__dict__.copy()
converted_block['transactions'] = [tx.__dict__ for tx in converted_block['transactions']]
for node in self.peer_nodes:
try:
resp = requests.post(f'http://{node}/broadcast-block', json={
'block': converted_block
})
if resp.status_code == 400 or resp.status_code == 500:
print('Block declined, needs resolving')
if resp.status_code == 409:
self.resolve_conflicts = True
except requests.exceptions.ConnectionError:
print(f'Peer {node} broadcast-block failed')
continue
return block
def add_block(self, block):
# converting the received dictionary transactions to transaction objects
transactions = [
Transaction(tx['sender'], tx['recipient'], tx['amount'],
tx['signature']) for tx in block['transactions']
]
proof_is_valid = Verification.valid_proof(transactions[:-1],
block['previous_hash'],
block['proof'])
hashes_match = hash_block(self.chain[-1]) == block['previous_hash']
if not proof_is_valid or not hashes_match:
return False
converted_block = Block(block['index'], block['previous_hash'],
transactions, block['proof'],
block['timestamp'])
self.__chain.append(converted_block)
# Removing transaction from open_transaction if they are in the mined block
stored_transactions = self.__open_transactions[:]
for itx in block['transactions']:
for opentx in stored_transactions:
if opentx.sender == itx['sender'] and opentx.recipient == itx[
'recipient'] and opentx.amount == itx[
'amount'] and opentx.signature == itx['signature']:
try:
self.__open_transactions.remove(opentx)
except ValueError:
print('Item was alredy removed')
self.save_data()
return True
def mine_block(self):
# prevent adding transaction when no wallet loaded
if self.public_key is None:
return None
# index [-1] accesses the last block of the chain
last_block = self.__chain[-1]
hashed_block = hash_block(last_block)
# We copy the list open_transaction with the ':' range selector to
# copy the whole list
# In complex objects like lists,tuples,sets,dictionary just assigning
# a new value
# with '=' just copies the reference. So if we change the copied list
# it will also be changed in the original
copied_open_transactions = self.__open_transactions[:]
# We calculate the proof number without the mining reward.
# To validate the chain we need to remove the reward_transaction
# before validating it
proof = self.proof_of_work()
# verify each open_transactions signatures. if one signature doesn't
# verify correctly we abort the mining
# this is done without the MINING transaction
for tx in copied_open_transactions:
if not Wallet.verify_transaction_signature(tx):
return None
reward_transaction = Transaction('MINING', self.public_key,
MINING_REWARD, '')
copied_open_transactions.append(reward_transaction)
block = Block(len(self.__chain), hashed_block,
copied_open_transactions, proof)
self.__chain.append(block)
# Empty open transaction files and save the datas
self.__open_transactions = []
self.save_data()
# Broadcasting new block
for node in self.__peer_nodes:
url = 'http://{}/broadcast-block'.format(node)
converted_block = block.__dict__.copy()
converted_block['transactions'] = [
tx.__dict__ for tx in converted_block['transactions']
]
try:
response = requests.post(url, json={'block': converted_block})
if response.status_code == 400 or response.status_code == 500:
print('Block declined!')
# when broadcasting block to peers returns a 409 message then
# set reolve_conflicts. see node.py broadcast_block
if response.status_code == 409:
self.resolve_conflicts = True
except requests.exceptions.ConnectionError:
continue
return block
def proof_of_work(self):
last_block = self.__chain[-1]
last_hash = hash_block(last_block)
proof = 0
while not Verification.valid_proof(self.__open_transactions, last_hash,
proof):
proof += 1
print(f"The proof number is: {proof}")
return proof
def validate_blockchain(cls, blockchain):
""" Validates the blockchain. """
is_valid = True
print("Validating the blockchain...")
for i, block in enumerate(blockchain):
if i == 0:
continue
else:
prev_block = blockchain[i - 1]
prev_block_hash = hash_block(prev_block)
print(f"[debug]: Comparing current block[{i}] ({block})")
print(
f"[debug]: and previous block[{i-1}] ({prev_block})")
print(
f"[debug]: Current",
f"block[prev_block_hash] == prev_block_hash",
f"({block.prev_block_hash} == {prev_block_hash})? ",
end="",
)
if block.prev_block_hash == prev_block_hash:
print(f"{GRN}Match!{NRM}")
else:
print(f"{RED}MIS-MATCH{NRM}!")
is_valid = False
print(f"[debug]: Verifying proof of block[{i}] ({block})")
print(
f"[debug]: Comparing first {cls.POW_DIGITS} digits",
f"to match '{cls.POW_PATTERN}' in the hash created from:",
)
txs_without_mining_reward = block.transactions[:-1]
print(
f"[debug]: Transactions ({txs_without_mining_reward})",
f"last block hash ({block.prev_block_hash}) and proof",
f"({block.proof})",
)
if cls.valid_proof(
txs_without_mining_reward,
block.prev_block_hash,
block.proof,
):
proof_succeeded = True
else:
proof_succeeded = False
is_valid = False
print()
guess_str = cls.generate_guess_string(
txs_without_mining_reward,
block.prev_block_hash,
block.proof,
)
print(f"[debug]: guess_str: ({guess_str})")
if proof_succeeded:
print(f"[debug]: Proof {GRN}Succeeded{NRM}!")
else:
print(f"[debug]: Proof {RED}FAILED{NRM}!")
return is_valid
def proof_of_work(self):
last_block = self.__chain[-1]
last_hash = hash_block(last_block)
proof = 0
while not Verification.valid_proof(self.__open_transaction, last_hash,
proof):
proof += 1
# Printing the number of hashes done to check the proof.
# print(proof)
return proof
def verify_chain(cls, blockchain):
"""Verifies whether the block are matching or not."""
for index, block in enumerate(blockchain):
if index == 0:
continue
if block.previous_hash != hash_block(blockchain[index - 1]):
return False
if not cls.valid_proof(block.transactions[:-1],
block.previous_hash, block.proof):
print("Proof of work is Invalid!!!")
return False
return True
def verify_chain(cls, get_balance, difficulty, chain):
chain_copy = chain[:]
for idx, block in enumerate(chain_copy):
if idx > 0:
if block.previous_hash != hash_block(chain_copy[idx - 1]):
return False
if not cls.valid_proof(block.transactions[:-1],
block.previous_hash, block.proof,
difficulty):
return False
if not all([
Verification.verify_tx(tx, get_balance)
for tx in block.transactions[:-1]
]):
return False
return True
def verify_chain(cls, blockchain):
# With enumerate we change the list to a Tuple so we can unpack it
# with idx-value pairs
for (index, block) in enumerate(blockchain):
if index < 1:
continue
if block.previous_hash != hash_block(blockchain[index - 1]):
print("Previous hash is invalid!")
return False
# We remove the last transaction with the range operator [:-1].
# It's the mining reward
# When we mine we don't include it in the proof of work
if not cls.valid_proof(block.transactions[:-1],
block.previous_hash, block.proof):
print("Proof of work is invalid")
return False
return True
def mine_block(self):
""" Adds a block of current transactions to the blockchain. """
if self.hosting_node is None:
return None
# reward the miner
reward_tx = Transaction(MINING_OWNER, self.hosting_node, None,
MINING_REWARD)
# make a copy in order to preserve open_txs
new_txs = self.__open_txs[:]
# verify the new transactions before adding the reward transaction
for tx in new_txs:
if not Wallet.verify_tx(tx):
return None
new_txs.append(reward_tx)
# add the current transactions
last_block = self.__chain[-1]
last_block_hash = hash_block(last_block)
proof = self.proof_of_work(self.__open_txs, last_block_hash)
block = Block(len(self.__chain), last_block_hash, proof, new_txs)
self.__chain.append(block)
self.__participants.add(self.hosting_node)
self.__open_txs = []
self.save_data()
return block
def add_block(self, block):
txs = [Transaction(tx['sender'], tx['recipient'], tx['signature'], tx['amount']) for tx in block['transactions']]
# Check proof is correct and previous hashes matches
# The txs[-1] is so to skip our reward tx because we calculate the proof without it.
if not Verification.valid_proof(txs[:-1], block['previous_hash'], block['proof'], self.difficulty) or not hash_block(self.chain[-1]) == block['previous_hash']:
return False
self.chain.append(Block(block['index'], block['previous_hash'], txs, block['proof'], block['timestamp']))
# If we got a block with some of our opentx's inside we need to remove these open tx's
stored_txs = self.open_transactions[:]
for itx in block['transactions']:
for opentx in stored_txs:
if opentx.sender == itx['sender'] and opentx.recipient == itx['recipient'] and opentx.amount == itx['amount'] and opentx.signature == itx['signature']:
try:
self.open_transactions.remove(opentx)
except ValueError:
print('Item was already removed')
self.save_data()
return True
def proof_of_work(self):
proof = 0
while not Verification.valid_proof(self.open_transactions, hash_block(self.chain[-1]), proof, self.difficulty):
proof += 1
return proof