blockchain.py

# -*- coding: utf-8 -*-
"""
Created on Mon May  4 00:25:35 2020

@author: smshi
"""
import hashlib
import json
import logging
import sys
import time

from ecdsa import NIST256p
from ecdsa import VerifyingKey

#自分で作ったので標準ワイぶらりとは分ける
import utils

MINING_DIFFICULTY = 3
MINING_SENDER = 'THE BLOCKCHAIN'
MINING_REWARD = 1.0

logging.basicConfig(level=logging.INFO, stream=sys.stdout)
logger = logging.getLogger(__name__)


#ブロックチェーンのクラス生成
class Blockchain(object):
	
	def __init__(self, blockchain_address=None, port=None):
		self.transaction_pool = []
		self.chain = []
		self.create_block(0, 'init hash')
		self.blockchain_address = blockchain_address
		self.port = port

		
	def create_block(self, nonce, previous_hash):
		block = utils.sorted_dict_by_key({
				'timestamp': time.time(),
				'transactions': self.transaction_pool,
				'nonce': nonce,
				'previous_hash': previous_hash
				})
		self.chain.append(block)
		self.transaction_pool = []
		return block
	
	def hash(self, block):
		sorted_block = json.dumps(block, sort_keys=True)#jsonでdictを読み出すときdampで文字列に変換、sort_key＝Trueでsort
		return hashlib.sha256(sorted_block.encode()).hexdigest()
	
	def add_transaction(self, sender_blockchain_address,
					    recipient_blockchain_address, value,
					    sender_public_key=None, signature=None):
		transaction = utils.sorted_dict_by_key({
				'sender_blockchain_address': sender_blockchain_address,
				'recipient_blockchain_address': recipient_blockchain_address,
				'value': float(value)
		})

		#マイニングのときにはしトランザクションの検証はしなくともいい
		if sender_blockchain_address == MINING_SENDER:
			self.transaction_pool.append(transaction)
			return True

		if self.verify_transaction_signature(
			sender_public_key, signature, transaction):

			#if self.calculate_total_amount(sender_blockchain_address) < float(value):
			#	logger.error({'action': 'add_transaction', 'error': 'no_value'})
			#	return False			

			self.transaction_pool.append(transaction)
			return True
		return False

	def create_transaction(self, sender_blockchain_address,
					    recipient_blockchain_address, value,
					    sender_public_key, signature):

		is_transacted = self.add_transaction(
			sender_blockchain_address, recipient_blockchain_address,
			value, sender_public_key, signature)

		#TODO
		#sync

		return is_transacted




		self.transaction_pool.append(transaction)
		return True
	
	def verify_transaction_signature(self, sender_public_key, signature, transaction):
		sha256 = hashlib.sha256()
		sha256.update(str(transaction).encode('utf-8'))
		message = sha256.digest()
		signature_byte = bytes().fromhex(signature)
		verifing_key = VerifyingKey.from_string(
			bytes().fromhex(sender_public_key), curve=NIST256p)
		verified_key = verifing_key.verify(signature_byte, message)
		return verified_key

	def valid_proof(self, transactions, previous_hash, 
				    nonce,difficulty=MINING_DIFFICULTY):
		guess_block = utils.sorted_dict_by_key({
				'transactions': transactions,
				'nonce': nonce,
				'previous_hash': previous_hash
		})
		guess_hash = self.hash(guess_block)
		return guess_hash[:difficulty] == '0'*difficulty
	
	def proof_of_work(self):
		transactions = self.transaction_pool.copy()
		previous_hash = self.hash(self.chain[-1])
		nonce = 0
		while self.valid_proof(transactions, previous_hash, nonce) is False:
			nonce += 1
		return nonce
	
	def mining(self):
		self.add_transaction(
				sender_blockchain_address=MINING_SENDER,
				recipient_blockchain_address=self.blockchain_address,
				value=MINING_REWARD)
		nonce = self.proof_of_work()
		previous_hash = self.hash(self.chain[-1])
		self.create_block(nonce, previous_hash)
		logger.info({'action': 'mining','status': 'success'})
		return True
	
	def calculate_total_amount(self, blockchain_address):
		total_amount = 0.0
		for block in self.chain:
			for transaction in block['transactions']:
				value = float(transaction['value'])
				if blockchain_address == transaction['recipient_blockchain_address']:
					 total_amount += value
				if blockchain_address == transaction['sender_blockchain_address']:
					total_amount -= value
		return total_amount