research/cycle_finding_function_coll...

50 lines
1.2 KiB
Python

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