trying for preimage attack
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@ -5,7 +5,10 @@ Dirty hash we were covered in an excercise for Week 16 of 2023 in cryptography
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import math
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import random
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DEFINED_INITIAL = bytearray(b'\xa5\xa5\xa5\xa5\x5a\x5a\x5a\x55\x55\x55\xaa\xaa\xaa')
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DEFINED_INITIAL = bytearray(b'\xa5\xa5\xa5\xa5\x5a\x5a\x5a\x5a\x55\x55\x55\x55\xaa\xaa\xaa\xaa')
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# the hash we want to find in the preimage attacks
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# comes from 'AAAA'
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THE_HASH = bytearray(b'\xe4\xe4\xe4\xe4\xa5\xa5\xa5\xa5\xaa\xaa\xaa\xaa\x55\x55\x55\x55')
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def trash_hash(input: bytearray) -> bytearray:
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#print("original len is %s" % len(input))
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@ -45,17 +48,6 @@ def trash_hash(input: bytearray) -> bytearray:
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return A
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def use():
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some_bytes = bytearray(b'AAAA');
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print("hashed: %s" % some_bytes.hex())
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print('='*80)
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hashed = trash_hash(some_bytes)
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print('='*80)
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print("hashed: %s" % hashed.hex())
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def test_collision(a: bytearray, b: bytearray) -> bool:
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return trash_hash(a) == trash_hash(b)
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def main():
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payload_a = bytearray(b"AAAA")
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# works, but is too cheap
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#payload_b = bytearray(b"AAAA\xff\xff")
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@ -63,6 +55,35 @@ def main():
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print("a: %s\nb: %s" % (trash_hash(payload_a).hex(), trash_hash(payload_b).hex()))
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print("identical: %s" % test_collision(payload_a, payload_b))
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def test_collision(a: bytearray, b: bytearray) -> bool:
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return trash_hash(a) == trash_hash(b)
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def test_against_hash(input: bytearray, target_hash: bytearray) -> bool:
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hashed = trash_hash(input)
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print("hashed variant:\t%s" % hashed.hex())
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print("should be:\t%s" % THE_HASH.hex())
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return trash_hash(input) == target_hash
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def first_preimage():
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print("Trying to find a message that produces %s" % THE_HASH.hex())
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# a xor b = c
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# c xor b = a
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target = bytearray(b'\ff' * 16)
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input = bytearray(b'\00' * 16)
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between = bytearray(16)
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# this is an arbituary target
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# should work for anything
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target[0] = ord('A')
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for i in range(0, 16):
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between[i] = target[i] ^ THE_HASH[i]
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input[i] = between[i] ^ THE_HASH[i]
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print(test_against_hash(input, THE_HASH))
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def main():
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first_preimage()
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def bruteForce() -> bool:
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payload_a = bytearray(b"AAAA")
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foundCollision = False
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