以下是使用Python编写简单的区块链的步骤：
- 安装需要的库
pip install hashlib
pip install flask
- 创建区块链的类
import hashlib
import json
from time import time
class Blockchain:
def __init__(self):
self.chain = []
self.current_transactions = []
# 创建创世块
self.new_block(previous_hash=1, proof=100)
def new_block(self, proof, previous_hash=None):
"""
创建新的区块
:param proof: <int> 工作量证明算法提供的证明
:param previous_hash: (Optional) <str> 前一个区块的 hash 值
:return: <dict> 新的区块
"""
block = {
'index': len(self.chain) + 1,
'timestamp': time(),
'transactions': self.current_transactions,
'proof': proof,
'previous_hash': previous_hash or self.hash(self.chain[-1]),
}
# 重置当前交易列表
self.current_transactions = []
self.chain.append(block)
return block
- 创建创世块和区块的添加方法
class Blockchain:
...
def new_block(self, proof, previous_hash=None):
...
def new_transaction(self, sender, recipient, amount):
"""
创建新的交易信息，将交易信息添加到当前交易列表
:param sender: <str> 发送者地址
:param recipient: <str> 接收者地址
:param amount: <int> 金额
:return: <int> 保存这个交易信息的区块的索引
"""
self.current_transactions.append({
'sender': sender,
'recipient': recipient,
'amount': amount,
})
return self.last_block['index'] + 1
@staticmethod
def hash(block):
"""
给一个区块生成 SHA-256 值
:param block: <dict> 区块
:return: <str>
"""
block_string = json.dumps(block, sort_keys=True).encode()
return hashlib.sha256(block_string).hexdigest()
@property
def last_block(self):
return self.chain[-1]
def proof_of_work(self, last_proof):
"""
简单的工作量证明算法:
- 查找一个 p' 使得 hash(pp') 以4个0开头
- p 是上一个区块的证明, p' 是当前的证明
:param last_proof: <int>
:return: <int>
"""
proof = 0
while self.valid_proof(last_proof, proof) is False:
proof += 1
return proof
@staticmethod
def valid_proof(last_proof, proof):
"""
验证工作量证明是否有效: 是否 hash(last_proof, proof) 以4个0开头?
:param last_proof: <int> Previous Proof
:param proof: <int> Current Proof
:return: <bool> True if correct, False if not.
"""
guess = f'{last_proof}{proof}'.encode()
guess_hash = hashlib.sha256(guess).hexdigest()
return guess_hash[:4] == "0000"
- 创建Flask Web应用程序
from uuid import uuid4
from flask import Flask, jsonify, request
# 创建一个节点名称
node_identifier = str(uuid4()).replace('-', '')
# 实例化flask
app = Flask(__name__)
# 实例化区块链
blockchain = Blockchain()
@app.route('/mine', methods=['GET'])
def mine():
# 挖掘新的区块
last_block = blockchain.last_block
last_proof = last_block['proof']
proof = blockchain.proof_of_work(last_proof)
# 给工作量证明的节点提供奖励.
# 发送者为 "0" 表明是新挖出的币
blockchain.new_transaction(
sender="0",
recipient=node_identifier,
amount=1,
)
# 添加新的区块到区块链中
previous_hash = blockchain.hash(last_block)
block = blockchain.new_block(proof, previous_hash)
response = {
'message': "New Block Forged",
'index': block['index'],
'transactions': block['transactions'],
'proof': block['proof'],
'previous_hash': block['previous_hash'],
}
return jsonify(response), 200
@app.route('/transactions/new', methods=['POST'])
def new_transaction():
values = request.get_json()
# 检查请求中的必需字段是否在POST中
required = ['sender', 'recipient', 'amount']
if not all(k in values for k in required):
return 'Missing values', 400
# 创建一个新的交易
index = blockchain.new_transaction(values['sender'], values['recipient'], values['amount'])
response = {'message': f'Transaction will be added to Block {index}'}
return jsonify(response), 201
@app.route('/chain', methods=['GET'])
def full_chain():
response = {
'chain': blockchain.chain,
'length': len(blockchain.chain),
}
return jsonify(response), 200
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
- 运行应用程序并测试
运行应用程序：
$ python blockchain.py
使用POST请求创建新的交易：
import requests
url = "http://localhost:5000/transactions/new"
values = {
"sender": "my address",
"recipient": "someone else's address",
"amount": 5
}
response = requests.post(url, json=values)
print(response)
使用GET请求获取完整的区块链：
import requests
url = "http://localhost:5000/chain"
response = requests.get(url)
print(response.json())
使用GET请求挖掘新的区块：文章来源：https://www.toymoban.com/news/detail-858452.html
import requests
url = "http://localhost:5000/mine"
response = requests.get(url)
print(response.json())
以上就是使用Python编写简单的区块链的过程。当然，这只是一个简单的示例，实际上实现一个真正有用的区块链需要更多的工作和细节。文章来源地址https://www.toymoban.com/news/detail-858452.html
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