Python实现类似比特币的加密货币区块链的创建与交易实例

import hashlib as hasher

class Block:
 def __init__(self, index, timestamp, data, previous_hash):
  self.index = index
  self.timestamp = timestamp
  self.data = data
  self.previous_hash = previous_hash
  self.hash = self.hash_block()
 
 def hash_block(self):
  sha = hasher.sha256()
  sha.update(str(self.index) + 
        str(self.timestamp) + 
        str(self.data) + 
        str(self.previous_hash))
  return sha.hexdigest()

import hashlib as hasher
 
class Block:
 def __init__(self, index, timestamp, data, previous_hash):
  self.index = index
  self.timestamp = timestamp
  self.data = data
  self.previous_hash = previous_hash
  self.hash = self.hash_block()
 
 def hash_block(self):
  sha = hasher.sha256()
  sha.update(str(self.index) + 
        str(self.timestamp) + 
        str(self.data) + 
        str(self.previous_hash))
  return sha.hexdigest()

import datetime as date

def create_genesis_block():
 # Manually construct a block with
 # index zero and arbitrary previous hash
 return Block(0, date.datetime.now(), "Genesis Block", "0")

import datetime as date
 
def create_genesis_block():
 # Manually construct a block with
 # index zero and arbitrary previous hash
 return Block(0, date.datetime.now(), "Genesis Block", "0")

def next_block(last_block):
 this_index = last_block.index + 1
 this_timestamp = date.datetime.now()
 this_data = "Hey! I'm block " + str(this_index)
 this_hash = last_block.hash
 return Block(this_index, this_timestamp, this_data, this_hash)

def next_block(last_block):
 this_index = last_block.index + 1
 this_timestamp = date.datetime.now()
 this_data = "Hey! I'm block " + str(this_index)
 this_hash = last_block.hash
 return Block(this_index, this_timestamp, this_data, this_hash)

# Create the blockchain and add the genesis block
blockchain = [create_genesis_block()]
previous_block = blockchain[0]

# How many blocks should we add to the chain
# after the genesis block
num_of_blocks_to_add = 20

# Add blocks to the chain
for i in range(0, num_of_blocks_to_add):
 block_to_add = next_block(previous_block)
 blockchain.append(block_to_add)
 previous_block = block_to_add
 # Tell everyone about it!
 print "Block #{} has been added to the blockchain!".format(block_to_add.index)
 print "Hash: {}n".format(block_to_add.hash)

# Create the blockchain and add the genesis block
blockchain = [create_genesis_block()]
previous_block = blockchain[0]
 
# How many blocks should we add to the chain
# after the genesis block
num_of_blocks_to_add = 20
 
# Add blocks to the chain
for i in range(0, num_of_blocks_to_add):
 block_to_add = next_block(previous_block)
 blockchain.append(block_to_add)
 previous_block = block_to_add
 # Tell everyone about it!
 print "Block #{} has been added to the blockchain!".format(block_to_add.index)
 print "Hash: {}n".format(block_to_add.hash)

{
 "from": "71238uqirbfh894-random-public-key-a-alkjdflakjfewn204ij",
 "to": "93j4ivnqiopvh43-random-public-key-b-qjrgvnoeirbnferinfo",
 "amount": 3
}


{
 "from": "71238uqirbfh894-random-public-key-a-alkjdflakjfewn204ij",
 "to": "93j4ivnqiopvh43-random-public-key-b-qjrgvnoeirbnferinfo",
 "amount": 3
}

$ pip install flask # 首先安装 Web 服务器框架
1
$ pip install flask # 首先安装 Web 服务器框架
Python

from flask import Flask
from flask import request
node = Flask(__name__)
# Store the transactions that
# this node has in a list
this_nodes_transactions = []
@node.route('/txion', methods=['POST'])
def transaction():
 if request.method == 'POST':
  # On each new POST request,
  # we extract the transaction data
  new_txion = request.get_json()
  # Then we add the transaction to our list
  this_nodes_transactions.append(new_txion)
  # Because the transaction was successfully
  # submitted, we log it to our console
  print "New transaction"
  print "FROM: {}".format(new_txion['from'])
  print "TO: {}".format(new_txion['to'])
  print "AMOUNT: {}\n".format(new_txion['amount'])
  # Then we let the client know it worked out
  return "Transaction submission successful\n"
node.run()

from flask import Flask
from flask import request
node = Flask(__name__)
# Store the transactions that
# this node has in a list
this_nodes_transactions = []
@node.route('/txion', methods=['POST'])
def transaction():
 if request.method == 'POST':
  # On each new POST request,
  # we extract the transaction data
  new_txion = request.get_json()
  # Then we add the transaction to our list
  this_nodes_transactions.append(new_txion)
  # Because the transaction was successfully
  # submitted, we log it to our console
  print "New transaction"
  print "FROM: {}".format(new_txion['from'])
  print "TO: {}".format(new_txion['to'])
  print "AMOUNT: {}\n".format(new_txion['amount'])
  # Then we let the client know it worked out
  return "Transaction submission successful\n"
node.run()

# ...blockchain
# ...Block class definition
miner_address = "q3nf394hjg-random-miner-address-34nf3i4nflkn3oi"
def proof_of_work(last_proof):
 # Create a variable that we will use to find
 # our next proof of work
 incrementor = last_proof + 1
 # Keep incrementing the incrementor until
 # it's equal to a number divisible by 9
 # and the proof of work of the previous
 # block in the chain
 while not (incrementor % 9 == 0 and incrementor % last_proof == 0):
  incrementor += 1
 # Once that number is found,
 # we can return it as a proof
 # of our work
 return incrementor
@node.route('/mine', methods = ['GET'])
def mine():
 # Get the last proof of work
 last_block = blockchain[len(blockchain) - 1]
 last_proof = last_block.data['proof-of-work']
 # Find the proof of work for
 # the current block being mined
 # Note: The program will hang here until a new
 #    proof of work is found
 proof = proof_of_work(last_proof)
 # Once we find a valid proof of work,
 # we know we can mine a block so 
 # we reward the miner by adding a transaction
 this_nodes_transactions.append(
  { "from": "network", "to": miner_address, "amount": 1 }
 )
 # Now we can gather the data needed
 # to create the new block
 new_block_data = {
  "proof-of-work": proof,
  "transactions": list(this_nodes_transactions)
 }
 new_block_index = last_block.index + 1
 new_block_timestamp = this_timestamp = date.datetime.now()
 last_block_hash = last_block.hash
 # Empty transaction list
 this_nodes_transactions[:] = []
 # Now create the
 # new block!
 mined_block = Block(
  new_block_index,
  new_block_timestamp,
  new_block_data,
  last_block_hash
 )
 blockchain.append(mined_block)
 # Let the client know we mined a block
 return json.dumps({
   "index": new_block_index,
   "timestamp": str(new_block_timestamp),
   "data": new_block_data,
   "hash": last_block_hash
 }) + "\n"

# ...blockchain
# ...Block class definition
miner_address = "q3nf394hjg-random-miner-address-34nf3i4nflkn3oi"
def proof_of_work(last_proof):
 # Create a variable that we will use to find
 # our next proof of work
 incrementor = last_proof + 1
 # Keep incrementing the incrementor until
 # it's equal to a number divisible by 9
 # and the proof of work of the previous
 # block in the chain
 while not (incrementor % 9 == 0 and incrementor % last_proof == 0):
  incrementor += 1
 # Once that number is found,
 # we can return it as a proof
 # of our work
 return incrementor
@node.route('/mine', methods = ['GET'])
def mine():
 # Get the last proof of work
 last_block = blockchain[len(blockchain) - 1]
 last_proof = last_block.data['proof-of-work']
 # Find the proof of work for
 # the current block being mined
 # Note: The program will hang here until a new
 #    proof of work is found
 proof = proof_of_work(last_proof)
 # Once we find a valid proof of work,
 # we know we can mine a block so 
 # we reward the miner by adding a transaction
 this_nodes_transactions.append(
  { "from": "network", "to": miner_address, "amount": 1 }
 )
 # Now we can gather the data needed
 # to create the new block
 new_block_data = {
  "proof-of-work": proof,
  "transactions": list(this_nodes_transactions)
 }
 new_block_index = last_block.index + 1
 new_block_timestamp = this_timestamp = date.datetime.now()
 last_block_hash = last_block.hash
 # Empty transaction list
 this_nodes_transactions[:] = []
 # Now create the
 # new block!
 mined_block = Block(
  new_block_index,
  new_block_timestamp,
  new_block_data,
  last_block_hash
 )
 blockchain.append(mined_block)
 # Let the client know we mined a block
 return json.dumps({
   "index": new_block_index,
   "timestamp": str(new_block_timestamp),
   "data": new_block_data,
   "hash": last_block_hash
 }) + "\n"

@node.route('/blocks', methods=['GET'])
def get_blocks():
 chain_to_send = blockchain
 # Convert our blocks into dictionaries
 # so we can send them as json objects later
 for block in chain_to_send:
  block_index = str(block.index)
  block_timestamp = str(block.timestamp)
  block_data = str(block.data)
  block_hash = block.hash
  block = {
   "index": block_index,
   "timestamp": block_timestamp,
   "data": block_data,
   "hash": block_hash
  }
 # Send our chain to whomever requested it
 chain_to_send = json.dumps(chain_to_send)
 return chain_to_send
def find_new_chains():
 # Get the blockchains of every
 # other node
 other_chains = []
 for node_url in peer_nodes:
  # Get their chains using a GET request
  block = requests.get(node_url + "/blocks").content
  # Convert the JSON object to a Python dictionary
  block = json.loads(block)
  # Add it to our list
  other_chains.append(block)
 return other_chains
def consensus():
 # Get the blocks from other nodes
 other_chains = find_new_chains()
 # If our chain isn't longest,
 # then we store the longest chain
 longest_chain = blockchain
 for chain in other_chains:
  if len(longest_chain) < len(chain):
   longest_chain = chain
 # If the longest chain wasn't ours,
 # then we set our chain to the longest
 blockchain = longest_chain

@node.route('/blocks', methods=['GET'])
def get_blocks():
 chain_to_send = blockchain
 # Convert our blocks into dictionaries
 # so we can send them as json objects later
 for block in chain_to_send:
  block_index = str(block.index)
  block_timestamp = str(block.timestamp)
  block_data = str(block.data)
  block_hash = block.hash
  block = {
   "index": block_index,
   "timestamp": block_timestamp,
   "data": block_data,
   "hash": block_hash
  }
 # Send our chain to whomever requested it
 chain_to_send = json.dumps(chain_to_send)
 return chain_to_send
def find_new_chains():
 # Get the blockchains of every
 # other node
 other_chains = []
 for node_url in peer_nodes:
  # Get their chains using a GET request
  block = requests.get(node_url + "/blocks").content
  # Convert the JSON object to a Python dictionary
  block = json.loads(block)
  # Add it to our list
  other_chains.append(block)
 return other_chains
def consensus():
 # Get the blocks from other nodes
 other_chains = find_new_chains()
 # If our chain isn't longest,
 # then we store the longest chain
 longest_chain = blockchain
 for chain in other_chains:
  if len(longest_chain) < len(chain):
   longest_chain = chain
 # If the longest chain wasn't ours,
 # then we set our chain to the longest
 blockchain = longest_chain

curl "localhost:5000/txion" \
   -H "Content-Type: application/json" \
   -d '{"from": "akjflw", "to":"fjlakdj", "amount": 3}'

curl "localhost:5000/txion" \
   -H "Content-Type: application/json" \
   -d '{"from": "akjflw", "to":"fjlakdj", "amount": 3}'

curl localhost:5000/mine

curl localhost:5000/mine

{
 "index": 2,
 "data": {
  "transactions": [
   {
    "to": "fjlakdj",
    "amount": 3,
    "from": "akjflw"
   },
   {
    "to": "q3nf394hjg-random-miner-address-34nf3i4nflkn3oi",
    "amount": 1,
    "from": "network"
   }
  ],
  "proof-of-work": 36
 },
 "hash": "151edd3ef6af2e7eb8272245cb8ea91b4ecfc3e60af22d8518ef0bba8b4a6b18",
 "timestamp": "2017-07-23 11:23:10.140996"
}

{
 "index": 2,
 "data": {
  "transactions": [
   {
    "to": "fjlakdj",
    "amount": 3,
    "from": "akjflw"
   },
   {
    "to": "q3nf394hjg-random-miner-address-34nf3i4nflkn3oi",
    "amount": 1,
    "from": "network"
   }
  ],
  "proof-of-work": 36
 },
 "hash": "151edd3ef6af2e7eb8272245cb8ea91b4ecfc3e60af22d8518ef0bba8b4a6b18",
 "timestamp": "2017-07-23 11:23:10.140996"
}