Pythonでブロックチェーンを組んでみる実験

pythonで遊ぶ機会があったのでお遊びで作ったもののメモ

import hashlib
import json
import datetime
import pickle

class Block:
    def __init__(self, index, timestamp, transaction, previous_hash):
        self.index = index
        self.timestamp = timestamp
        self.transaction = transaction
        self.previous_hash = previous_hash
        self.difficulty = 4 #難易度を追加
        self.property_dict = {str(i): j for i, j in self.__dict__.items()}
        self.now_hash = self.calc_hash()
        self.proof = None # プルーフを追加
        self.proof_hash = None # プルーフを追加して計算したハッシュ

    def calc_hash(self):
        block_string = json.dumps(self.property_dict, sort_keys=True).encode('ascii')
        return hashlib.sha256(block_string).hexdigest()

    # プルーフの検証用関数
    def check_proof(self, proof):
        proof_string = self.now_hash + str(proof)
        calced = hashlib.sha256(proof_string.encode("ascii")).hexdigest()
        if calced[:self.difficulty:].count('0') == self.difficulty:
            self.proof_hash = calced
            return True
        else:
            return False

    # プルーフを採掘するための関数
    def mining(self):
        proof = 0
        while True:
            if self.check_proof(proof):
                break
            else:
                proof += 1
        return proof

# トランザクションを生成
def new_transaction(sender, recipient, amount):
    transaction = {
        "差出人": sender,
        "あて先": recipient,
        "金額": amount,
    }
    return transaction

block_chain = []

block = Block(0, 0, [], '-') #最初のブロックを作成

block.proof = block.mining()

block_chain.append(block)

i=0
while datetime.datetime(2018, 11, 10, 3, 20) > datetime.datetime.now(): 
# for i in range(10):
    # i=0
    # i=i+1
    block = Block(i+1, str(datetime.datetime.now()), new_transaction("太郎", "花子", 100), block_chain[i].now_hash)
    block.proof = block.mining()
    block_chain.append(block)


    with open('sample.pickle', mode='wb') as f:
        pickle.dump(block_chain, f)
        f.close()

    i=i+1

    for block in block_chain:
        for key, value in block.__dict__.items():
            print(key, ':', value)
        print("")
    print("==== ==== ==== ==== ==== ==== ==== ==== ====")

#    for block in block_chain:
#        for key, value in block.__dict__.items():
#            print(key, ':', value)
#        print("")

'''
print("==== ==== ==== ==== ==== ==== ==== ==== ====")
with open('sample.pickle', mode='rb') as f:
    pickle.load(f)
    f.close()

    for block in block_chain:
        for key, value in block.__dict__.items():
            print(key, ':', value)
        print("")
'''

'''
for block in block_chain:
    for key, value in block.__dict__.items():
        print(key, ':', value)
    print("")
'''

参考