55 lines
1.9 KiB
Python
55 lines
1.9 KiB
Python
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import random
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# Attacker percent of hashpower
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alpha = 0.333
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# Probability attacker can win in a network race
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gamma = 0.0
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# Total blocks of attacker and honest miners
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attacker_blocks = 0
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honest_blocks = 0
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# At the start of each outer loop, the attacker and honest
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# chains are fully shared
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while attacker_blocks + honest_blocks < 100000:
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# 1-alpha: honest miner makes block, attacker accepts
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if random.random() > alpha:
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honest_blocks += 1
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continue
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# alpha: attacker makes block
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# 1-alpha: honest miners publish a block and catch up
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# Attacker publishes their block. They now have two
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# chances to win: (i) they make the next block, (ii)
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# the next block is made by an honest miner who saw
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# the attacker's block first
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if random.random() > alpha:
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# Alpha: attacker mines next block, publishes both blocks
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if random.random() < alpha:
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attacker_blocks += 2
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continue
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# 1-alpha: honest miners mine next block, publish
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# gamma: that honest miner saw the attacker's block first,
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# so the new winning chain contains one honest block and
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# one attacker block
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if random.random() < gamma:
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honest_blocks += 1
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attacker_blocks += 1
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# 1-gamma: that honest miner saw the honest block first,
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# so the winning chain contains two honest blocks
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else:
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honest_blocks += 2
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continue
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# alpha: attacker is now two blocks ahead
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state = [2, 0]
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# Keep going until attacker only one block ahead
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while state[0] - state[1] > 1:
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if random.random() > alpha:
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state[1] += 1
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else:
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state[0] += 1
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# Attacker publishes, overtakes honest chain
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attacker_blocks += state[0]
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print("Attacker blocks percentage: %.3f" %
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(attacker_blocks / (attacker_blocks + honest_blocks) * 100))
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