def bit_flip_CTR(CTR_oracle, target_bytes):
''' Flip bits in CBC cipher to produce target bytes at target block.'''
insertion = bytes(16)
work_cipher = CTR_oracle(insertion)
# Assuming we know the point at which our insertion is entered into this;
# it would be harder otherwise. We'll xor the cipher vs. our insertion.
keystream_section = bytes_xor(work_cipher[32:48], insertion)
# Now we xor the known section of keystream_section vs. our target_bytes.
# This is simpler than CBC bitflipping.
second_insertion = bytes_xor(keystream_section, target_bytes)
return work_cipher[:32] + second_insertion + work_cipher[48:]
def bit_flip_CBC(CBC_oracle, target_bytes, target_block, b_l=16):
''' Flip bits in CBC cipher to produce target bytes at target block.'''
insertion = bytes(16)
work_cipher = CBC_oracle(insertion)
# We know this is the plaintext; if we didn't, we would double our Z insertion.
plaintext_to_be_flipped = b';comment2=%20lik'
# The zero point that produced our known plaintext is this block; we need
# to treat it as the base from which we work.
insertion_cipher_block = work_cipher[32:48]
# Find the xor product of the target and known plaintext.
bytes_to_produce_target = bytes_xor(plaintext_to_be_flipped, target_bytes)
# Combine that product with the base cipherblock.
flipped_bits = bytes_xor(insertion_cipher_block, bytes_to_produce_target)
flipped_cipher = work_cipher[:32] + flipped_bits + work_cipher[48:]
return flipped_cipher
ciphers, if an English sentence is detected, return decryption.'''
min_len = min([len(cipher) for cipher in list_of_ciphers])
possible_key_streams = product(*possible_key_bytes)
dictionary = ct.load_dictionary()
for key_stream in possible_key_streams:
concat = b''.join(key_stream)
for cipher in list_of_ciphers:
work_cipher = cipher[:len(concat)]
decryption = b''.join(
[bytes([a ^ b]) for a, b in zip(cipher, concat)])
if ct.is_language(decryption, dictionary):
print('Likely key stream found.')
return concat
else:
print('Unable to find key stream.')
return None
static_key = os.urandom(16)
nonce = struct.pack('<Q', 0)
list_of_ciphers = make_ciphers(encrypt_AES_CTR, static_key, nonce, PLAINTEXTS)
nonce_slices = concatenate_nonce_slices(list_of_ciphers)
possible_key_stream = score_bytes(nonce_slices)
likely_key_stream = try_likely_bytes(possible_key_stream, list_of_ciphers)
if likely_key_stream:
for cipher in list_of_ciphers:
work_cipher = cipher[:len(likely_key_stream)]
print(ct.bytes_xor(work_cipher, likely_key_stream))
def retrieve_key(unencrypted):
''' From plaintext of unencrypted remix cipher, retrieve IV used as key.'''
return bytes_xor(unencrypted[:16], unencrypted[32:48])
min_len = min([len(cipher) for cipher in list_of_ciphers])
possible_key_streams = product(*possible_key_bytes)
dictionary = ct.load_dictionary()
for key_stream in possible_key_streams:
concat = b''.join(key_stream)
for cipher in list_of_ciphers:
work_cipher = cipher[:len(concat)]
decryption = b''.join([bytes([a ^ b]) for a,b
in zip(cipher, concat)])
if ct.is_language(decryption, dictionary):
print('Likely key stream found.')
return concat
else:
print('Unable to find key stream.')
return None
static_key = os.urandom(16)
nonce = struct.pack('<Q', 0)
list_of_ciphers = make_ciphers(encrypt_AES_CTR, static_key, nonce, PLAINTEXTS)
nonce_slices = concatenate_nonce_slices(list_of_ciphers)
possible_key_stream = score_bytes(nonce_slices)
likely_key_stream = try_likely_bytes(possible_key_stream, list_of_ciphers)
if likely_key_stream:
for cipher in list_of_ciphers:
work_cipher = cipher[:len(likely_key_stream)]
print(ct.bytes_xor(work_cipher, likely_key_stream))
def xor_hexes(hex_one, hex_two):
bytes_one = ct.hex_to_bytes(hex_one)
bytes_two = ct.hex_to_bytes(hex_two)
xored_bytes = ct.bytes_xor(bytes_one, bytes_two)
return ct.bytes_to_hex(xored_bytes)
def retrieve_key(unencrypted):
''' From plaintext of unencrypted remix cipher, retrieve IV used as key.'''
return bytes_xor(unencrypted[:16], unencrypted[32:48])
