def proof_of_work(self, mysql):
#Start by verifying all the transactions in the pool
verified_transactions = []
cur = mysql.connection.cursor()
result = cur.execute("SELECT * FROM blockchain_transactions")
transactions = cur.fetchall()
#We are going to verify all the transactions in the pool before we add them to the block .....
#then clear the transaction pool by deleting all the transactions in the database ....
if result > 0:
for transaction in transactions:
id = transaction['id']
data = json.loads(transaction['transaction'])
signature_string = transaction['signature']
string_transaction = json.dumps(data, sort_keys = True).encode()
signature = eval(signature_string)
public, key2 = keys.get_public_keys_from_sig(signature, string_transaction, curve=curve.secp256k1, hashfunc=ecdsa.sha256)
is_valid = ecdsa.verify(signature, string_transaction, public, curve.secp256k1, ecdsa.sha256)
if is_valid is True:
verified_transactions.append(data)
cur.execute("DELETE from blockchain_transactions WHERE id=%s", [id])
mysql.connection.commit()
#Now we add the transactions to the new block
the_time = datetime.now()
prev_hash = ''
def is_valid(self):
if self.signature is None:
return True
if len(self.signature) == 0 and self.to_address is None:
return False
hash_tx = self.calculate_hash()
pubkey = keys.get_public_keys_from_sig(self.signature, hash_tx, curve=curve.P256, hashfunc=sha256)
valid = ecdsa.verify(self.signature, hash_tx, pubkey[0], hashfunc=sha256)
return valid
def test():
data = {
"fullNames":
'Bertha Matshidiso Kgokong',
"practiceNumber":
'1234567890',
"notes":
'I believe, we will make it to the moon and we will do it in this century'
}
private, public = import_key('/home/zatosh/keys/secp256k1.key')
transaction = account.create_transaction(data)
string_transaction = json.dumps(transaction, sort_keys=True).encode()
signature = ecdsa.sign(string_transaction,
private,
curve=curve.secp256k1,
hashfunc=ecdsa.sha256)
##-----------------------------------------
#Assume we are now - publishing the transaction
transaction['signature'] = json.dumps(signature)
to_send = json.dumps(transaction, sort_keys=True)
#Now Let us See of This code will work . . . .
trans_result = to_send
transaction1 = json.loads(trans_result)
#Add the Transaction to the pool
string_signature1 = transaction1['signature']
signature1 = eval(string_signature1)
transaction1.pop('signature')
string_transaction1 = json.dumps(transaction1, sort_keys=True).encode()
key1, key2 = keys.get_public_keys_from_sig(signature1,
string_transaction1,
curve=curve.secp256k1,
hashfunc=ecdsa.sha256)
is_valid = ecdsa.verify(signature1, string_transaction1, key1,
curve.secp256k1, ecdsa.sha256)
print(
'Just received transaction broadcast {}: and added it to transaction pool'
.format(transaction1))
return "<h3>If this is true, the signatures did match - or else. ---> {}</h3>".format(
is_valid)
def extract_secp256r1_public_keys(r, s, message):
"""Extract the public keys from r, s, message which generated by secp256r1
:param str r: The r part of signature
:param str s: The s part of signature
:param str message: The message for signature
:rtype: list
:return: The public keys
"""
public_key_point = keys.get_public_keys_from_sig((int(r, 16), int(s, 16)), message, curve.P256, hashfunc=keccak_256)
public_key_list = []
for i in public_key_point:
x = str(hex(i.x)[2:])
y = str(hex(i.y)[2:])
if len(x) < 64:
x = '0' * (64 - len(x)) + x
if len(y) < 64:
y = '0' * (64 - len(y)) + y
public_key = '0x' + x + y
public_key_list.append(public_key)
return public_key_list
def awaiting_transaction_broadcast():
while True:
trans_result = transaction_subscriber.recv_json()
transaction = json.loads(trans_result)
if 'signature' in transaction:
#Add the Transaction to the pool
string_signature = transaction['signature']
signature = eval(string_signature)
transaction.pop('signature')
string_transaction = json.dumps(transaction,
sort_keys=True).encode()
key1, key2 = keys.get_public_keys_from_sig(signature,
string_transaction,
curve=curve.secp256k1,
hashfunc=ecdsa.sha256)
blockchain.add_transaction(key1, transaction, signature,
transaction['transaction_id'], mysql)
print(
'Just received transaction broadcast {}: and added it to transaction pool'
.format(transaction))
def awaiting_chain_broadcast():
while True:
chain_result = chain_subscriber.recv_json()
new_chain = json.loads(chain_result)
print('We just received a new chain \n {}'.format(new_chain))
if not 'signature' in new_chain:
#Get our chain from the database
cur = mysql.connection.cursor()
result = cur.execute("SELECT * FROM blockchain_chain")
chain = cur.fetchall()
if chain == []:
#The chain table is empty ..... save this chain to our database
for new_block in new_chain:
block = new_block['block']
nonce = new_block['nonce']
hash = new_block['hash']
prev_hash = new_block['prev_hash']
timestamp = new_block['timestamp']
data = new_block['data']
cur.execute(
"INSERT INTO blockchain_chain(block, nonce, hash, prev_hash, timestamp, data) VALUES(%s, %s, %s, %s, %s, %s)",
(block, nonce, hash, prev_hash, timestamp, data))
mysql.connection.commit()
cur.close()
pass
else:
cur.close()
if len(new_chain) > len(chain):
#We already have a chain table in our database saved - we just need to confirm chain is valid
if blockchain.is_chain_valid(new_chain, mysql):
#The received chain is valid - genesis blocks match and all block hashes and nonces also match
new_transactions = new_chain[len(new_chain) -
1]['data']
verified_transactions = []
for transaction in new_transactions:
id = transaction['id']
data = json.loads(transaction['transaction'])
signature_string = transaction['signature']
string_transaction = json.dumps(
data, sort_keys=True).encode()
signature = eval(signature_string)
public, key2 = keys.get_public_keys_from_sig(
signature,
string_transaction,
curve=curve.secp256k1,
hashfunc=ecdsa.sha256)
is_transaction_valid = ecdsa.verify(
signature, string_transaction, public,
curve.secp256k1, ecdsa.sha256)
if is_transaction_valid:
verified_transactions.append(data)
print('Valid Transaction -> {}'.format(data))
else:
print(
'The following transaction is not valid, cannot accept this new chain: {}'
.format(transaction))
pass
#Replace our chain with new chain - if chain is valid and all transactions in the last block are also valid
cur = mysql.connection.cursor()
#Start by deleting the current chain from database
cur.execute("DELETE from blockchain_chain")
mysql.connection.commit()
#We also need to delete everything from the transaction table - because the transactions have been mined in this block.
cur.execute("DELETE from blockchain_transactions")
mysql.connection.commit()
#then save new blockchain in to our database
for new_block in new_chain:
block = new_block['block']
nonce = new_block['nonce']
hash = new_block['hash']
prev_hash = new_block['prev_hash']
timestamp = new_block['timestamp']
data = new_block['data']
cur.execute(
"INSERT INTO blockchain_chain(block, nonce, hash, prev_hash, timestamp, data) VALUES(%s, %s, %s, %s, %s, %s)",
(block, nonce, hash, prev_hash, timestamp,
data))
mysql.connection.commit()
cur.close()
else:
#Received chain is not valid
print('Received chain is not valid --> DISCARD')
pass
else:
print(
'Received chain is shorter than or equal to the chain we already have -- > DISCARD'
)
pass
else:
#This is a transaction - transaction function will handle . . . .
pass