如何用Python实现区块链的PoW共识机制？

本文共计408个文字，预计阅读时间需要2分钟。

原始实现（Python 2 版本）：pythonimport hashlibimport time

def proof_of_work(target_difficulty): prefix='0' * target_difficulty nonce=0 while True: hash_result=hashlib.sha256(str(nonce).encode()).hexdigest() if hash_result.startswith(prefix): return nonce nonce +=1 time.sleep(0.01)

target_difficulty=5nonce=proof_of_work(target_difficulty)print(Found nonce:, nonce)

改进后的代码（基于 Python 3 特性）：pythonimport hashlibimport time

def proof_of_work(target_difficulty): prefix='0' * target_difficulty nonce=0 while True: hash_result=hashlib.sha256(str(nonce).encode()).hexdigest() if hash_result.startswith(prefix): return nonce nonce +=1 time.sleep(0.01)

target_difficulty=5nonce=proof_of_work(target_difficulty)print(Found nonce:, nonce)

原始实现（python2 版本）

​​github.com/santisiri/proof-of-work​​

依据python3特性改进后：

#!/usr/bin/env python
# example of proof of work algorithm

import hashlib
import time

max_nonce = 2 ** 32 # 4 billion

def proof_of_work(header, difficulty_bits):

target = 2 ** (256-difficulty_bits)
for nonce in range(max_nonce):
hash_result = hashlib.sha256((str(header)+str(nonce)).encode("utf-8")).hexdigest()
if int(hash_result, 16) < target:
print( "Success with nonce %d" % nonce )
print( "Hash is %s" % hash_result )
return (hash_result, nonce)

print( "Failed after %d (max_nonce) tries" % nonce )
return nonce

if __name__ == '__main__':

nonce = 0
hash_result = ''

for difficulty_bits in range(32):

difficulty = 2 ** difficulty_bits

print( "" )
print( "Difficulty: %ld (%d bits)" % (difficulty, difficulty_bits) )

print( "Starting search..." )

start_time = time.time()

new_block = 'test block with transactions' + hash_result

(hash_result, nonce) = proof_of_work(new_block, difficulty_bits)

end_time = time.time()

elapsed_time = end_time - start_time

print( "Elapsed time: %.4f seconds" % elapsed_time )

if elapsed_time > 0:

hash_power = float(int(nonce)/elapsed_time)
print( "Hashing power: %ld hashes per second" % hash_power )

运行结果：

注：

具体原理不知。

参考：

​​简述目前相对成熟的区块链共识算法​​