mirror of
https://github.com/bitcoinbook/bitcoinbook
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2f0d7d8c3a
The commit ab5ae32bae is the last commit
for the second edition, so all changes since then are dropped except for
several commits for the third edition authored by Andreas Antonopoulos.
No attempt is made to remove CC-BY-SA or other licensed content present
in the already-published first or second editions.
This revert may itself be reverted for versions of the book published
under CC-BY-SA.
65 lines
1.8 KiB
Python
Executable File
65 lines
1.8 KiB
Python
Executable File
#!/usr/bin/env python
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# example of proof-of-work algorithm
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import hashlib
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import time
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try:
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long # Python 2
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xrange
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except NameError:
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long = int # Python 3
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xrange = range
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max_nonce = 2 ** 32 # 4 billion
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def proof_of_work(header, difficulty_bits):
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# calculate the difficulty target
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target = 2 ** (256 - difficulty_bits)
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for nonce in xrange(max_nonce):
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hash_result = hashlib.sha256(str(header) + str(nonce)).hexdigest()
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# check if this is a valid result, below the target
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if long(hash_result, 16) < target:
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print("Success with nonce %d" % nonce)
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print("Hash is %s" % hash_result)
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return (hash_result, nonce)
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print("Failed after %d (max_nonce) tries" % nonce)
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return nonce
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if __name__ == '__main__':
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nonce = 0
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hash_result = ''
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# difficulty from 0 to 31 bits
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for difficulty_bits in xrange(32):
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difficulty = 2 ** difficulty_bits
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print("Difficulty: %ld (%d bits)" % (difficulty, difficulty_bits))
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print("Starting search...")
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# checkpoint the current time
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start_time = time.time()
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# make a new block which includes the hash from the previous block
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# we fake a block of transactions - just a string
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new_block = 'test block with transactions' + hash_result
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# find a valid nonce for the new block
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(hash_result, nonce) = proof_of_work(new_block, difficulty_bits)
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# checkpoint how long it took to find a result
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end_time = time.time()
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elapsed_time = end_time - start_time
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print("Elapsed Time: %.4f seconds" % elapsed_time)
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if elapsed_time > 0:
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# estimate the hashes per second
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hash_power = float(long(nonce) / elapsed_time)
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print("Hashing Power: %ld hashes per second" % hash_power)
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