工作量证明算法

 区块链中一种工作量证明算法

 #!/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):
 # calculate the difficulty target
 target = 2 ** (256-difficulty_bits)
 for nonce in xrange(max_nonce):
 hash_result = hashlib.sha256(str(header)+str(nonce)).hexdigest()
 # check if this is a valid result, below the target
 if long(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 = ''
 # difficulty from 0 to 31 bits
 for difficulty_bits in xrange(32):
 difficulty = 2 ** difficulty_bits
 print "Difficulty: %ld (%d bits)" % (difficulty, difficulty_bits)
 print "Starting search..."
 # checkpoint the current time
 start_time = time.time()
 # make a new block which includes the hash from the previous block
 # we fake a block of transactions - just a string
 new_block = 'test block with transactions' + hash_result
 # find a valid nonce for the new block
 (hash_result, nonce) = proof_of_work(new_block, difficulty_bits)
 # checkpoint how long it took to find a result
 end_time = time.time()
 elapsed_time = end_time - start_time
 print "Elapsed Time: %.4f seconds" % elapsed_time
 if elapsed_time > 0:
 # estimate the hashes per second
 hash_power = float(long(nonce)/elapsed_time)
 print "Hashing Power: %ld hashes per second" % hash_power