50 lines
1.2 KiB
Python
50 lines
1.2 KiB
Python
from ethereum.utils import sha3
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import sys
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STEPLENGTH = 100
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dp = {}
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def step(inp):
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return sha3('function_'+inp.encode('hex')+'()')[:4]
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def run_round(inp):
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orig_inp = inp
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for i in range(STEPLENGTH):
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inp = step(inp)
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if inp in dp.keys():
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print 'Found!', i + 1, repr(inp)
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return(True, i + 1, inp)
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dp[inp] = orig_inp
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return(False, None, inp)
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y = '\xff' * 4
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orig_y = y
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rounds = 0
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while 1:
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print 'Running round', rounds
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rounds += 1
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x, t, y2 = run_round(y)
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if x:
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prev1, prev2 = y, dp[y2]
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assert prev1 != prev2
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# print '-----'
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for i in range(STEPLENGTH - t):
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# print repr(prev2)
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prev2 = step(prev2)
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# print '-----'
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for i in range(t):
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# print repr(prev1), repr(prev2)
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next1 = step(prev1)
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next2 = step(prev2)
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if next1 == next2:
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print 'Found!'
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print 'function_'+prev1.encode('hex')+'()'
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print 'function_'+prev2.encode('hex')+'()'
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sys.exit()
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prev1, prev2 = next1, next2
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# print repr(prev1), repr(prev2)
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raise Exception("Something weird happened")
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else:
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y = y2
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