def partial_validation():
values = request.form
required = ['root', 'path', 'sender', 'recipient', 'value']
# Check that the required fields are in the POST data
if not all(k in values for k in required):
return 'Missing values', 400
root = values.get('root')
path = json.loads(values.get('path'))
transaction = Transaction(values.get('sender'), values.get('recipient'), values.get('value'))
if values.get('signature'):
transaction.signature = values.get('signature')
h = sha256(str(transaction.to_json()).encode()).hexdigest()
new_root = blockchain.partialValidation(path, h)
result = root == new_root
return jsonify(result), 200
def merkle_path():
values = request.form
required = ['sender', 'recipient', 'value']
# Check that the required fields are in the POST data
if not all(k in values for k in required):
return 'Missing values', 400
transaction = Transaction(values.get('sender'), values.get('recipient'), values.get('value'))
if values.get('signature'):
transaction.signature = values.get('signature')
path = blockchain.merkle_path(transaction)
if len(path) > 0:
root = path[-1]
path = path[:-1]
return jsonify(path), 200
def new_transaction_signed():
values = request.form
required = ['sender', 'recipient_address', 'value', 'signature']
# Check that the required fields are in the POST data
if not all(k in values for k in required):
return 'Missing values', 400
transaction = Transaction(values['sender'], values['recipient_address'], values['value'])
transaction.signature = values['signature']
transaction_result = blockchain.add_new_transaction(transaction)
if transaction_result:
response = {'message': 'Transaction will be added to Block'}
return jsonify(response), 201
else:
response = {'message': 'Invalid Transaction!'}
return jsonify(response), 406
def search_block_with_transaction(self, transactionHash):
'''return block that matches given transaction hash'''
fullchain = [json.loads(block) for block in self.chain]
for block in fullchain[::-1]:
for trans in block['transaction']:
trans = json.loads(trans)
new_trans = Transaction(trans['sender'], trans['recipient'],
trans['value'])
if 'signature' in trans.keys():
new_trans.signature = trans['signature']
new_transHash = sha256(str(
new_trans.to_json()).encode()).hexdigest()
if transactionHash == new_transHash:
return block
return False
def merkle_path(self, transaction: Transaction):
'''return merkle path of given transaction'''
path = []
transactionHash = sha256(str(
transaction.to_json()).encode()).hexdigest()
block = self.search_block_with_transaction(transactionHash)
leaves = []
if block:
for trans in block['transaction']:
trans = json.loads(trans)
new_trans = Transaction(trans['sender'], trans['recipient'],
trans['value'])
if 'signature' in trans.keys():
new_trans.signature = trans['signature']
new_transHash = sha256(str(
new_trans.to_json()).encode()).hexdigest()
leaves.append(new_transHash)
path = self._merklePath(leaves, transactionHash, [])
path.append(block['merkle_root'])
return path
def valid_chain(self, chain: List[str]) -> bool:
'''check if a blockchain (all blocks) is valid'''
current_index = 0
chain = json.loads(chain)
# load and check every block from the blockchain
while current_index < len(chain):
block = json.loads(chain[current_index])
current_block = Block(block['index'], block['transaction'],
block['timestamp'], block['previous_hash'])
current_block.merkle_root = block['merkle_root']
current_block.nonce = block['nonce']
current_block.difficulty = block['difficulty']
# if the current block is NOT the last block
if current_index + 1 < len(chain):
# if the hash value of the current block != previous block's hash value of the next block, then reject
if current_block.compute_hash() != json.loads(
chain[current_index + 1])['previous_hash']:
return False
# check if the current block is an instance from the list of chain
if isinstance(current_block.transaction, list):
for transaction in current_block.transaction:
transaction = json.loads(transaction)
# Skip block reward because it does not have signature
if transaction['sender'] == 'Block_Reward':
continue
current_transaction = Transaction(transaction['sender'],
transaction['recipient'],
transaction['value'])
current_transaction.signature = transaction['signature']
# check if digital signature of each transaction is valid, if not then reject
if not current_transaction.verify_transaction_signature():
return False
# check if hash value of the current block is not valid, if yes then reject
if not self.is_valid_proof(current_block, block['hash']):
return False
current_index += 1
return True
