블록체인 구조 만들기

https://medium.com/crypto-currently/lets-build-the-tiniest-blockchain-e70965a248b

위 글을 참고해서 파이썬으로 블록체인 구조를 구현해 보았다.

블록

아래 코드의 블록체인 구조의 한 블럭은 인덱스(index), 생성 시간(timestamp), hex encoding된 형태의 데이터(data), 이전 블럭의 해시값(prev), 스스로의 해시값(hash)을 가진다.

코드

import hashlib
import datetime
import binascii

class Block:
    def __init__(self, index, timestamp, data, prev):
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.prev = prev
        self.hash = self.hash_block()

    def hash_block(self):
        sha = hashlib.sha256()
        sha.update((str(self.index) + str(self.timestamp) + 
                   str(self.data) + str(self.prev)).encode())
        return sha.hexdigest()

def encode_data(data):
    return binascii.hexlify(bytes(data, 'UTF-8')).decode()

def create_genesis_block():
    return Block(0, datetime.datetime.now(), encode_data('Genesis!!'), '0')

def next_block(prev_block, block_data):
    block_index = prev_block.index + 1
    block_timestamp = datetime.datetime.now()
    block_hash = prev_block.hash
    return Block(block_index, block_timestamp, block_data, block_hash)

blockchain = [create_genesis_block()]
prev_block = blockchain[0]
print(blockchain)
print('data : ' + blockchain[0].data)
print('hash : ' + blockchain[0].hash)
print('prev : ' + blockchain[0].prev)


new_block = next_block(prev_block, encode_data('주노귀요미><'))
blockchain.append(new_block)
prev_block = new_block
print(blockchain)

print('data : ' + blockchain[1].data)
print('hash : ' + blockchain[1].hash)
print('prev : ' + blockchain[1].prev)

실행 결과

PS C:\Users\JunhoYeo\Desktop\blockmemo> python .\app.py
[<__main__.Block object at 0x04B58830>]
data : 47656e657369732121
hash : 5c0bf0826a551a4802eb3b4c8bf3d10a0a48617a3c11430cd9cb511285148a0f
prev : 0
[<__main__.Block object at 0x04B58830>, <__main__.Block object at 0x04B58850>]
data : eca3bceb85b8eab780ec9a94ebafb83e3c
hash : 40645d4a608cec928cffe4bdd91d550e0cf258b3506edd8f41968fc481fe32ec
prev : 5c0bf0826a551a4802eb3b4c8bf3d10a0a48617a3c11430cd9cb511285148a0f
PS C:\Users\JunhoYeo\Desktop\blockmemo>