def _decrypt_subtitles(self, data, iv, id):
data = bytes_to_intlist(base64.b64decode(data.encode('utf-8')))
iv = bytes_to_intlist(base64.b64decode(iv.encode('utf-8')))
id = int(id)
def obfuscate_key_aux(count, modulo, start):
output = list(start)
for _ in range(count):
output.append(output[-1] + output[-2])
# cut off start values
output = output[2:]
output = list(map(lambda x: x % modulo + 33, output))
return output
def obfuscate_key(key):
num1 = int(floor(pow(2, 25) * sqrt(6.9)))
num2 = (num1 ^ key) << 5
num3 = key ^ num1
num4 = num3 ^ (num3 >> 3) ^ num2
prefix = intlist_to_bytes(obfuscate_key_aux(20, 97, (1, 2)))
shaHash = bytes_to_intlist(
sha1(prefix + str(num4).encode('ascii')).digest())
# Extend 160 Bit hash to 256 Bit
return shaHash + [0] * 12
key = obfuscate_key(id)
decrypted_data = intlist_to_bytes(aes_cbc_decrypt(data, key, iv))
return zlib.decompress(decrypted_data)
def obfuscate_key(key):
num1 = int(floor(pow(2, 25) * sqrt(6.9)))
num2 = (num1 ^ key) << 5
num3 = key ^ num1
num4 = num3 ^ (num3 >> 3) ^ num2
prefix = intlist_to_bytes(obfuscate_key_aux(20, 97, (1, 2)))
shaHash = bytes_to_intlist(
sha1(prefix + str(num4).encode('ascii')).digest())
# Extend 160 Bit hash to 256 Bit
return shaHash + [0] * 12
def aes_decrypt_text(data, password, key_size_bytes):
"""
Decrypt text
- The first 8 Bytes of decoded 'data' are the 8 high Bytes of the counter
- The cipher key is retrieved by encrypting the first 16 Byte of 'password'
with the first 'key_size_bytes' Bytes from 'password' (if necessary filled with 0's)
- Mode of operation is 'counter'
@param {str} data Base64 encoded string
@param {str,unicode} password Password (will be encoded with utf-8)
@param {int} key_size_bytes Possible values: 16 for 128-Bit, 24 for 192-Bit or 32 for 256-Bit
@returns {str} Decrypted data
"""
NONCE_LENGTH_BYTES = 8
data = bytes_to_intlist(base64.b64decode(data.encode('utf-8')))
password = bytes_to_intlist(password.encode('utf-8'))
key = password[:key_size_bytes] + [0] * (key_size_bytes - len(password))
key = aes_encrypt(key[:BLOCK_SIZE_BYTES], key_expansion(key)) * (
key_size_bytes // BLOCK_SIZE_BYTES)
nonce = data[:NONCE_LENGTH_BYTES]
cipher = data[NONCE_LENGTH_BYTES:]
class Counter(object):
__value = nonce + [0] * (BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES)
def next_value(self):
temp = self.__value
self.__value = inc(self.__value)
return temp
decrypted_data = aes_ctr_decrypt(cipher, key, Counter())
plaintext = intlist_to_bytes(decrypted_data)
return plaintext
