Blockchain - HackMD

# Blockchain > for scientific exhibition 2018 > [name=牟展祐] [time=Mon, Dec 18, 2017 9:16 PM] # [Github](https://github.com/William-Mou/Blockchain) ## 動機 --- ## Some Webs ## 參考資源 :smile:[57屆科展：使用區塊鏈開發可監督捐款之公開募捐平台](http://activity.ntsec.gov.tw/activity/race-1/57/pdf/052505.pdf) ### 乙太访運作與實作 [以太坊白皮书](https://github.com/ethereum/wiki/wiki/%5B%E4%B8%AD%E6%96%87%5D-%E4%BB%A5%E5%A4%AA%E5%9D%8A%E7%99%BD%E7%9A%AE%E4%B9%A6) :smile:[智能合約](https://blog.gasolin.idv.tw/2017/08/13/got-my-ens-domain/) [以太坊錢包Parity](https://medium.com/taipei-ethereum-meetup/%E5%9C%A8parity%E5%89%B5%E5%BB%BA%E4%BB%A5%E5%A4%AA%E5%9D%8A%E9%8C%A2%E5%8C%85-b2c2977378fc) [教練，我”只”想學Solidity](https://medium.com/taipei-ethereum-meetup/%E6%95%99%E7%B7%B4-%E6%88%91-%E5%8F%AA-%E6%83%B3%E5%AD%B8solidity-92b7ba8054f5) :smile:[收到我的ENS網域啦 gasolin.eth](https://blog.gasolin.idv.tw/2017/08/13/got-my-ens-domain/) :smile:[如何撰寫智能合約(Smart Contract)?(I)](https://blog.gasolin.idv.tw/2017/09/06/howto-write-a-smart-contract/) :smile:[如何撰寫智能合約(Smart Contract)?(II)建立加密代幣 ](https://blog.gasolin.idv.tw/2017/09/11/howto-write-a-simple-token/) :smile:[如何撰寫智能合約(Smart Contract)?(III)建立標準代幣 ](https://blog.gasolin.idv.tw/2017/09/16/howto-write-an-erc20-compatible-token/) [如何撰寫智能合約(Smart Contract)?(IV)加入單元測試](https://blog.gasolin.idv.tw/2018/01/02/howto-write-a-contract-test/) [区块链开发（一）搭建基于以太坊的私有链环境](http://blog.csdn.net/sportshark/article/details/51855007) https://mshk.top/2017/11/go-ethereum-1-7-2-mist-0-9-2-token/ ```=json { "nonce": "0x0000000000000042", "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000", "difficulty": "0x400", "alloc": {}, "coinbase": "0x3333333333333333333333333333333333333333", "timestamp": "0x0", "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000", "extraData": "0x", "gasLimit": "0x8000000", "config": {} } ``` geth --datadir "%cd%" init piccgenesis.json geth --identity "PICCetherum" --rpc --rpccorsdomain "*" --datadir "%cd%/" --port "30303" --rpcapi "db,eth,net,web3" --networkid 95518 console [区块链开发（二）部署和运行第一个以太坊智能合约](http://blog.csdn.net/sportshark/article/details/52249607) [区块链开发（三）编写调试第一个以太坊智能合约](http://blog.csdn.net/fidelhl/article/details/52524434) [Solisity文檔](http://solidity.readthedocs.io/en/latest/) [Solidity中文語法表](http://www.tryblockchain.org/Solidity%E6%99%BA%E8%83%BD%E5%90%88%E7%BA%A6%E6%96%87%E4%BB%B6%E7%BB%93%E6%9E%84.html) [Solidity語法教學](http://blog.csdn.net/diandianxiyu_geek/article/details/77877841) [如何在私有区块链上编写、部署以及与以太坊进行交互的智能合约](http://blog.csdn.net/dev_csdn/article/details/78893014) [台北乙太坊社群專欄](https://medium.com/taipei-ethereum-meetup) [Solidity撰寫智能合約與注意事項(一)](https://medium.com/taipei-ethereum-meetup/solidity%E6%92%B0%E5%AF%AB%E6%99%BA%E8%83%BD%E5%90%88%E7%B4%84%E8%88%87%E6%B3%A8%E6%84%8F%E4%BA%8B%E9%A0%85-%E4%B8%80-6c9eacc00168) [Solidity撰寫智能合約與注意事項(二)](https://medium.com/taipei-ethereum-meetup/solidity%E6%92%B0%E5%AF%AB%E6%99%BA%E8%83%BD%E5%90%88%E7%B4%84%E8%88%87%E6%B3%A8%E6%84%8F%E4%BA%8B%E9%A0%85-%E4%BA%8C-dd915bdeafa0) [合約與以太接收](https://ethereum.stackexchange.com/questions/27052/how-to-create-a-smart-contract-to-send-an-eth-tx-on-time) ### Python語法 :smile:[python2 廖雪峰教程](https://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000) :smile:[python3 廖雪峰教程](https://www.liaoxuefeng.com/wiki/0014316089557264a6b348958f449949df42a6d3a2e542c000) :smile:["@"裝飾器概念](https://foofish.net/python-decorator.html) :smile:[Python & Flask](http://blog.techbridge.cc/2017/06/03/python-web-flask101-tutorial-introduction-and-environment-setup/) ### 觀念建構 :smile:[區塊鏈技術概觀（一）：讓我們從歷史文本說起](https://finance.technews.tw/2017/08/01/block-chain-technology-overview/) :smile:[區塊鏈技術概觀（二）：資料分割與密碼學](https://technews.tw/2017/08/09/blockchain-principle-part-two/) :smile:[區塊鏈技術概觀（三）：多數決的運作結構](https://technews.tw/2017/08/16/blockchain-principle-part-three/) [區塊鏈技術指南](https://yeasy.gitbooks.io/blockchain_guide/content/) ### python實作 [用Python从零开始创建区块链](http://www.jianshu.com/p/cc6663cbbc41) [50 行 Python 代码构建一个区块链](http://blog.csdn.net/simple_the_best/article/details/75448617) ### 其他實作 [瀏覽器挖礦分析](https://4hou.win/wordpress/?p=9162) [javascript](http://robertvmp.pixnet.net/blog/post/24544521-javascript---入門觀念基礎教學) [Socket](http://beej-zhtw.netdpi.net/02-what-is-socket/2-1-two-internet-sockets) :smile:[Flask](http://dormousehole.readthedocs.io/en/latest/quickstart.html) ### 勞基法 [加班費試算](https://labweb.mol.gov.tw/) ## 一些個人想法一日半夜所思：中心思想：有鑒於「信任」成為了網路世界中的最後一道難題，區塊鏈這把鑰匙將成為下個10年的關鍵技術！而學習區塊鏈這多技術合成的概念，必能使個人與網路環境更趨於完善！幾個方向： 1.交易公平去中心：採比特幣技術，可以達到交易不受到任何一方掌控，我認為這對於未來得金融支付系統可以產生重大動搖！ 2.合約透明散中心：透過交易資料，使合約成為一種交易狀態，有望用於一但交易完成不可更改而大筆的交易，如土地、不動產交易，權力的轉移（著作權、親權等），以至於人口紀錄，戶籍遷移等等。 3.資訊永存分中心：若所有人民無法共同達到最高公民素養，那政府機制（中心機制）必仍然存在；如同若無法每個人都擁有相同電腦，那挖礦速度必存在差異。如此一來，縱使再怎麼強調烏托邦世界，一定程度的中心存在是不可避免的，那麼，能夠讓中心權利分治，變成為一關注重點。現今透過媒體等等來監督政府體制，但無法達到高效率同步，亦不能維持訊息完整度，經過一層轉手，資訊比有失真。故，透過區塊鏈不可更改，可快速傳播的特性，有望能夠達成全民監督政府資訊（透過軟件檢視政府是否串改資料），使過往諾言不可食言。願景：本科展願能對三方面做出淺分析與實作，又以2.3.為主要目標，希望能拋磚引玉，促進台灣區塊鏈新技術的發展。 ## 可運行代碼 ```python= import hashlib import json from textwrap import dedent from time import time from uuid import uuid4 from flask import Flask, jsonify, request from urllib.parse import urlparse import requests class Blockchain(object): def __init__(self): self.chain = [] self.current_transactions = [] self.nodes = set() # Create the genesis block self.new_block(previous_hash=1, proof=100) def register_node(self, address): """ Add a new node to the list of nodes :param address: <str> Address of node. Eg. 'http://192.168.0.5:5000' :return: None """ parsed_url = urlparse(address) self.nodes.add(parsed_url.netloc) def new_block(self, proof, previous_hash=None): # Creates a new Block and adds it to the chain """ 生成新块 :param proof: <int> The proof given by the Proof of Work algorithm :param previous_hash: (Optional) <str> Hash of previous Block :return: <dict> New Block """ block = { 'index': len(self.chain) + 1, 'timestamp': time(), 'transactions': self.current_transactions, 'proof': proof, 'previous_hash': previous_hash or self.hash(self.chain[-1]), } # Reset the current list of transactions self.current_transactions = [] self.chain.append(block) return block def new_transaction(self, sender, recipient, amount): """ 生成新交易信息，信息将加入到下一个待挖的区块中 :param sender: <str> Address of the Sender :param recipient: <str> Address of the Recipient :param amount: <int> Amount :return: <int> The index of the Block that will hold this transaction """ self.current_transactions.append({ 'sender': sender, 'recipient': recipient, 'amount': amount, }) return self.last_block['index'] + 1 @staticmethod #從外部非實體化調用函數 def hash(block): """ 生成块的 SHA-256 hash值 :param block: <dict> Block :return: <str> """ # We must make sure that the Dictionary is Ordered, or we'll have inconsistent hashes block_string = json.dumps(block, sort_keys=True).encode() return hashlib.sha256(block_string).hexdigest() @property #檢查參數後再傳入 def last_block(self): return self.chain[-1] @staticmethod def valid_proof(last_proof, proof): """ 验证证明: 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" def proof_of_work(self, last_proof): """ 简单的工作量证明: - 查找一个 p' 使得 hash(pp') 以4个0开头 - p 是上一个块的证明, 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 def valid_chain(self, chain): """ Determine if a given blockchain is valid :param chain: <list> A blockchain :return: <bool> True if valid, False if not """ last_block = chain[0] current_index = 1 while current_index < len(chain): block = chain[current_index] print(f'{last_block}') print(f'{block}') print("\n-----------\n") # Check that the hash of the block is correct if block['previous_hash'] != self.hash(last_block): return False # Check that the Proof of Work is correct if not self.valid_proof(last_block['proof'], block['proof']): return False last_block = block current_index += 1 return True def resolve_conflicts(self): """ 共识算法解决冲突使用网络中最长的链. :return: <bool> True 如果链被取代, 否则为False """ neighbours = self.nodes new_chain = None # We're only looking for chains longer than ours max_length = len(self.chain) # Grab and verify the chains from all the nodes in our network for node in neighbours: response = requests.get(f'http://{node}/chain') if response.status_code == 200: length = response.json()['length'] chain = response.json()['chain'] # Check if the length is longer and the chain is valid if length > max_length and self.valid_chain(chain): max_length = length new_chain = chain # Replace our chain if we discovered a new, valid chain longer than ours if new_chain: self.chain = new_chain return True return False # Instantiate our Node app = Flask(__name__) # Generate a globally unique address for this node node_identifier = str(uuid4()).replace('-', '') # Instantiate the Blockchain blockchain = Blockchain() @app.route('/mine', methods=['GET']) def mine(): # We run the proof of work algorithm to get the next proof... 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, ) # Forge the new Block by adding it to the chain block = blockchain.new_block(proof) 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() # Check that the required fields are in the POST'ed data required = ['sender', 'recipient', 'amount'] if not all(k in values for k in required): return 'Missing values', 400 # Create a new Transaction 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 @app.route('/nodes/register', methods=['POST']) def register_nodes(): values = request.get_json() print(values) nodes = values.get('nodes') if nodes is None: return "Error: Please supply a valid list of nodes", 400 for node in nodes: blockchain.register_node(node) response = { 'message': 'New nodes have been added', 'total_nodes': list(blockchain.nodes), } return jsonify(response), 201 @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 is authoritative', 'chain': blockchain.chain } return jsonify(response), 200 if __name__ == '__main__': app.run(host='0.0.0.0', port=5000) ```

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