基於python的區塊鏈技術核心原理實現

開發環境： win10+Anaconda+PyCharm

測試工具：Postman

代碼如下：

import hashlib
import json
import time
import uuid

from flask import Flask, jsonify, request
from urllib.parse import urlparse
from argparse import ArgumentParser

class Blockchain:
    def __init__(self):
        self.chain = []
        # 交易信息
        self.current_transactions = []
        self.nodes = set()
        self.new_block(proof=100, previous_hash=1)

    #節點註冊
    def register_node(self, address: str):
        #http://127.0.0.1:5001
        parsed_url = urlparse(address)
        self.nodes.add(parsed_url.netloc)

    #共識機制
    def resolve_conflicts(self):
        neighbours = self.nodes
        max_length = len(self.chain)
        new_chain = None
        for node in neighbours:
            response = request.get(f'http://{node}/chain')
            if response.status_code == 200:
                length = response.json()['length']
                chain = response.json()['chain']
                if length > max_length and self.valid_chain(chain):
                    max_length = length
                    new_chain = chain

        if new_chain:
            self.chain = new_chain
            return True

        return False

    #檢查區塊是否有效
    def valid_chain(self, chain)->bool:
        last_block =  chain[0]
        current_index = 1
        while current_index < len(chain):
            block = chain[current_index]
            if block["previous_hash"] != self.hash(last_block):
                return  False

            if not self.valid_proof(last_block["proof"],block["proof"]):
                return False

            last_block = block
            current_index += 1

        return True

        pass
    # 建立新的區塊
    def new_block(self, proof, previous_hash=None):
        block = {
            'index': len(self.chain) + 1,
            'timestamp': time.time(),
            'transaction': self.current_transactions,
            'proof': proof,
            'previous_hash': previous_hash or self.hash(self.last_block)
        }
        self.current_transactions = []
        self.chain.append(block)
        return block

    # 建立新的交易,參數：1.發送者 2.接收者 3.金額
    def new_transaction(self, sender, recipient, amount):
        self.current_transactions.append({
            'sender': sender,
            'recipient': recipient,
            'amount': amount
        })
        return self.last_block['index'] + 1

    # 計算區塊hash值,靜態方法
    @staticmethod
    def hash(block):
        block_string = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()

    # 獲取最後一個區塊，作爲一個屬性
    @property
    def last_block(self):
        return self.chain[-1]

    # 工作量證明
    def proof_of_work(self, last_proof: int) -> int:
        proof = 0
        while self.valid_proof(last_proof, proof) is False:
            proof += 1
        return proof

    def valid_proof(self, last_proof: int, proof: int) -> bool:
        guess = f'{last_proof}{proof}'.encode()
        guess_hash = hashlib.sha256(guess).hexdigest()
        if guess_hash[0:4] == "0000":
            return True
        else:
            return False

#創建一個 FLASK對象
app = Flask(__name__)

blockchain = Blockchain()

node_indentifier = str(uuid.uuid4()).replace("-", "")

#添加一個新的交易
@app.route('/transaction/new', methods=['POST'])
def new_transaction():
    values = request.get_json()
    required = ["sender", "recipient", "amount"]
    if values is None:
        return "MISSING VALUES", 400
    #檢查請求中是否已經帶好了三個參數
    if not all(k in values for k in required):
        return "MISSING VALUES", 400
    index = blockchain.new_transaction(values["sender"], values["recipient"], values["amount"])
    response = {"message": f'Transcation will be add to Block{index}'}
    return jsonify(response), 201

#挖礦/打包
@app.route("/mine", methods=['GET'])
def mine():
    #獲取上一個區塊，然後得到上一個區塊的工作量證明
    last_block = blockchain.last_block
    last_proof = last_block['proof']
    proof = blockchain.proof_of_work(last_proof)
    blockchain.new_transaction(sender="0", recipient=node_indentifier, amount=1)
    block = blockchain.new_block(proof, None)

    response = {
        "message": "new block forged",
        "index": block['index'],
        "transaction": block["transaction"],
        "proof": block["proof"],
        "previous_hash": block["previous_hash"]
    }
    return jsonify(response), 200

#返回整個區塊鏈信息
@app.route("/chain", methods=['GET'])
def full_chain():
    response = {
        "chain": blockchain.chain,
        "length": len(blockchain.chain)
    }
    return jsonify(response), 200
#節點註冊
@app.route("/node/register", methods=['post'])
def register_node():
    values = request.get_json()
    nodes = values.get("nodes")
    if nodes is None:
        return "Error :please supply a valid list of nodes"

    for node in nodes:
        blockchain.register_node(node)
    response = {
        "message": "new nodes have benn added",
        "total_nodes":list(blockchain.nodes)
    }
    return jsonify(response), 201

#解決衝突
@app.route('/nodes/resolve',methods=['get'])
def consensus():
    replaced = blockchain.resolve_conflicts()
    if replaced:
        response = {
            "message": "our chain was replaced",
            "new_chain": blockchain.chain
        }
    else:
        response = {
            "message": "our chain was authoritative",
            "new_chain": blockchain.chain
        }
    return jsonify(response), 200

if __name__ == '__main__':
    parser = ArgumentParser()
    #-p --port
    parser.add_argument('-p', '--port', default=5000, type=int, help="port to listen to")
    args = parser.parse_args()
    port = args.port
    app.run(host='127.0.0.1', port=5000)

 

部分測試用例

1.測試鏈接 ：http://127.0.0.1:5000/transaction/new

{
	"sender":"bysen",
	"recipient":"lucy",
	"amount":5
}

2.測試鏈接：http://127.0.0.1:5000/mine

{
	"sender":"bysen",
	"recipient":"lucy",
	"amount":5
}

3.測試鏈接：http://127.0.0.1:5000/node/register

{
	"nodes":["http://127.0.0.2:5001"]
}