import json
from Crypto.Hash import SHA
from Crypto.Signature import PKCS1_v1_5
from Crypto.PublicKey import RSA
from models import db, User
from collections import OrderedDict
from hashlib import sha512
import base64
class Transaction:
_id = 0 # Incremental id for each instance created
def __init__(self, sender_address, receiver_address, amount, transaction_inputs, ids,
genesis=False):
self.sender_address = sender_address # Sender's public key
self.receiver_address = receiver_address # Receiver's public key
self.amount = amount # Transfer Amount
self.transaction_id = str(ids)+str(Transaction._id) # Transaction Id
self.transaction_inputs = transaction_inputs # Previous Transaction Id
self.transaction_outputs = [] # {id: (Receiver/Sender Address, Amount/Change)}
self.signature = '' # Proof that sender requested transaction
self.change = 0
self.user_id = ids
if not genesis:
total_utxo = int(User.query.filter_by(id=ids).first().total_htbc)
self.change = total_utxo - self.amount
if self.change < 0:
self.change = 0
else:
self.change = -self.amount
self.transaction_outputs.append(
{str(self.user_id) + str(Transaction._id): (self.receiver_address, self.amount)})
Transaction._id += 1
self.transaction_outputs.append(
{str(self.user_id) + str(Transaction._id): (self.sender_address, self.change)})
else:
self.transaction_outputs.append({"0"+str(Transaction._id): (self.receiver_address,
self.amount)})
Transaction._id += 1
def to_od(self):
# Convert object to ordered dictionary (so it produces same results every time)
od = OrderedDict([
('sender_address', self.sender_address),
('receiver_address', self.receiver_address),
('amount', self.amount),
('transaction_id', self.transaction_id),
('transaction_inputs', self.transaction_inputs),
('transaction_outputs', self.transaction_outputs),
('signature', self.signature),
('change', self.change),
('user_id', self.user_id)
])
return od
def to_json(self):
return json.dumps(self.to_od(), default=str)
def get_hash(self):
return self.get_hash_obj().hexdigest()
def get_hash_obj(self):
return sha512(str(self.to_json()).encode('utf-8'))
def sign_transaction(self, private_key):
priv_key = RSA.importKey(private_key)
my_sign = PKCS1_v1_5.new(priv_key)
transaction = self.to_od()
h = SHA.new(json.dumps(transaction, default=str).encode('utf8'))
self.signature = base64.b64encode(my_sign.sign(h)).decode('utf8')
