dsp-blockchain/lib/transaction.py

import hashlib
import json
import time
import uuid

from lib.contract import Contract
from cryptography.fernet import Fernet
import rsa

class Transaction:
    def __init__(self):
        self.id = None
        self.data = None
        self.hash_value = None
        self.locked = False
        self.timestamp = 0
        self.sender = None
        self.receiver = None

    def from_serialized(self, jsonobj: str):
        obj = json.loads(jsonobj)
        self.id = obj['id']
        self.data = obj['data']
        self.timestamp = obj['timestamp']
        self.sender = obj['sender']
        self.receiver = obj['receiver']

    def set_serialized_contract(self, serialized):
        if not self.locked:
            self.id = str(uuid.uuid1())
            self.data = serialized
            self.log('Serialized contract set')
            return True
        return False

    def set_contract(self, contract: Contract):
        if not self.locked:
            self.id = str(uuid.uuid1())
            self.data = contract.serialize()
            self.log(f'Contract set: {contract.id} | {contract.title}')
            return True
        return False

    def serialize(self, out_json=False):
        obj = {
            'id': self.id,
            'timestamp': self.timestamp,
            'data': self.data,
            'sender': self.sender,
            'receiver': self.receiver
        }
        self.log(f'Serialized')
        if out_json:
            return json.dumps(obj, sort_keys=True)
        return obj

    def lock_hash_finish(self):
        if not self.locked:
            self.timestamp = int(time.time())
            self.locked = True
            self.hash()
            self.log('Locked')
            return True
        return False

    def file_open(file):
        key_file = open(file, 'rb')
        key_data = key_file.read()
        key_file.close()
        return key_data

    def hash(self):
        string_object = json.dumps(self.data, sort_keys=True)
        block_string = string_object.encode()

        # open the public key file
        pubkey = rsa.PublicKey.load_pkcs1(file_open('publickey.key')) #Sender public key - input field neccessary

        # create the cipher
        cipher = Fernet(pubkey)

        # encrypt the data
        encrypted_data = cipher.encrypt(block_string)


        #these lines only neccessary for key_encryption - solve the problem of bytes
        # open the symmetric key file for encryoting the file
        #skey = open('symmetric.key','rb')
        #key = skey.read()


        # encrypt the symmetric key file with the public key
        #encrypted_key = rsa.encrypt(key,pubkey)

        self.hash_value = encrypted_data
        self.log(f'Hashed: {self.hash_value}')

        return encrypted_data

    def log(self, text):
        print(f'[ TRANS ] {text}')