def create_block(self, nonce, prev_hash, block_hash):
block = Block(nonce, prev_hash, block_hash, len(self.chain) + 1, self.pendingTransaction)
if block.is_block_valid():
self.chain.append(block)
self.pendingTransaction = []
return block
return False
def test_second_block(self):
genesis_block = Block("other genesis transaction",
["other genesis transaction"])
second_block = Block(genesis_block.block_hash, ["second transaction"])
self.assertEqual(
"bc614d0f64f95f3bebbed0fc562b5dd6dec85db07cd6c2d217936d34bb77fbe6",
second_block.block_hash)
def generate_genesis_block(self):
# add genesis block
if len(self.chain) == 0:
print('Mining Block #0...')
genesis = Block([], 'genesis')
genesis.mine(self.difficulty)
self.chain.append(genesis.serialized)
def create_genesis_block(self):
"""
A function which generates the genesis block and appends it to
the chain.
* Such a block has an index of 0
* Such a block has a previous_hash of 0, and a valid hash.
"""
genesis_block = Block(0, [], 0, "0")
genesis_block.hash = genesis_block.compute_hash()
self.chain.append(genesis_block)
def add_block(self, miner_address):
# We reward those who mine with 1 coin, so we append a new transaction with this reward
self.pending_transactions.append(
Transaction('blockchain', miner_address,
1).serialized) # from blockchain, to miner, 1 coin
# construct a new block
new_block = Block(self.pending_transactions, self.chain[-1]['hash'])
print(f'Mining block #{len(self.chain)}...')
# mine it
new_block.mine(self.difficulty)
# and append to chain, cleaning the pending transaction ('cos we've already written them in the block)
self.chain.append(new_block.serialized)
self.pending_transactions = []
def mine(self):
"""
This function serves as an interface to add the pending
transactions to the blockchain by adding them to the block
and figuring out Proof Of Work.
"""
if not self.unconfirmed_transactions:
return False
last_block = self.get_last_block
new_block = Block(index=last_block.index + 1,
data=self.unconfirmed_transactions,
timestamp=time.time(),
previous_hash=last_block.hash)
proof = self.proof_of_work(new_block)
self.add_block(new_block, proof)
self.unconfirmed_transactions = []
return True
def verify_and_add_block():
"""
Adds a block mined by someone else to the node's chain.
The block is first verified by the node and then added to
the chain.
:return: a success/error string, HTTP error code
"""
block_data = request.get_json()
block = Block(block_data["index"], block_data["transactions"],
block_data["timestamp"], block_data["previous_hash"],
block_data["nonce"])
proof = block_data['hash']
added = blockchain.add_block(block, proof)
if not added:
return "The block was discarded by the node", 400
return "Block added to the chain", 201
def create_chain_from_dump(chain_dump):
"""
Creates a blockchain from given data.
:param chain_dump: the data
:return: the generated blockchain
"""
generated_blockchain = Blockchain()
generated_blockchain.create_genesis_block()
for idx, block_data in enumerate(chain_dump):
if idx == 0:
# We don't care about the genesis block.
continue
block = Block(block_data["index"], block_data["transactions"],
block_data["timestamp"], block_data["previous_hash"],
block_data["nonce"])
proof = block_data['hash']
added = generated_blockchain.add_block(block, proof)
if not added:
raise Exception("The chain dump is tampered!!")
return generated_blockchain
def test_genesis_block(self):
genesis_block = Block("genesis transaction", ["genesis transaction"])
self.assertEqual(
"46dcd5396770ce394ce0c8b259a0e6e7defb277e17bfc17ff17a51988fc9c2d2",
genesis_block.block_hash)
def get_random_block(self, block_number=None, prevhash=None):
block_number = block_number if block_number is not None else np.random.randint(
2000)
block = Block().to_dict(block_number=block_number)
block['transactions'] = self.get_transactions(2000)
return block
from blockchain.Block import Block
blockchain = []
genesis_block = Block("Chacellor on the brink...", [
"Satoshi sent 1 BTC to Victor", "Maria sent 5 BTC to Jenny",
"Satoshi sent 5 BTC to Hal Finney"
])
second_block = Block(genesis_block.block_hash, [
"Ivan sent 1 BTC to Jhonn", "Maria sent 5 BTC to Ivan",
"Satoshi sent 5 BTC to Victor"
])
third_block = Block(second_block.block_hash, ["A to C 5 BTC", "B to D 5 BTC"])
print("Block hash: Genesis Block")
print(genesis_block.block_hash)
print("Block hash: Second Block")
print(second_block.block_hash)
print("Block hash: Third Block")
print(third_block.block_hash)
def __init__(self, PORT):
self.chain = []
self.pendingTransaction = []
self.db = DBUtil('db/' + str(PORT))
self.networkNodes = self.db.get_network_node()
self.db.store_genesis_block(Block(1, ' ', '00000', 1, []))
def get_block_from_dict(self, block_dict):
return Block(nonce=block_dict['timestamp'],
number=block_dict['number'],
prevhash=block_dict['prevhash'])
def __init__(self, PORT):
self.chain = []
self.pendingTransaction = []
self.networkNodes = []
self.file = FileUtil('json/' + str(PORT) + '.json')
self.file.store_genesis_block(Block(1, '0000x', '0000x', 1, []))