def MD(message, H):
for block in blocks(message):
H = C(block, H)
return H
def MD(message):
H = 0xde98
for block in blocks(pad(message)):
H = C(block, H)
return H
if short_hash in long_hashes:
long_blocks = long_prefix + long_hashes[short_hash]
assert len(long_blocks) == block_size * num_blocks
assert MD(long_blocks, H) == short_hash
return (short_block, long_blocks, short_hash)
with open('paper-preimages.pdf', 'rb') as fp:
data = fp.read()
data = pad(data)
intermediates = []
H = 0x3fe4
for block in blocks(data):
intermediates.append(H)
H = C(block, H)
data_hash = H
expandable = []
H = 0x3fe4
for i in range(16):
(m1, m2, H) = find_collision(16 - i, H)
expandable.append((i, m1, m2, H))
# This sometimes fails. If it does, just run it again.
assert H in intermediates
index = intermediates.index(H)
assert index > len(expandable)
len_leaves, roots, glue_num, leaves, all_nodes = best_root
# Our length: glue_num blocks, 64 for the message, one glue block
end_block = b'\0' + (glue_num * 16 + 64 + 16).to_bytes(8, 'big') + b'\0' * 7
end_hash = roots[0][2]
print('Root block hash', end_hash)
end_hash = C(end_block, end_hash)
print('Prediction with hash: %d' % end_hash)
message = b'A Tesla will be able to drive itself across the country in 2018.'
assert len(message) == 64
H = 0xde98
for block in blocks(message):
H = C(block, H)
print('H of message', H)
leaf_index = {}
for leaf in leaves:
leaf_index[leaf[0]] = leaf
# Find a block that map from H to anything in leaf_index
while True:
block = os.urandom(16)
glued_h = C(block, H)
if glued_h in leaf_index:
break
