def _convert_special_byte_arr_to_text(special_byte_arr):
"""Конвертирует байтовый массив с сообщением обратно в сообщение."""
if not Steganography._check_message_availability(special_byte_arr):
raise Exception(strings.DATA_CORRUPTED)
encoded_text = special_byte_arr[:-36].decode("UTF-8")
decoded_text = Crypter.decode_text(encoded_text)
return decoded_text
def _check_message_availability(special_byte_arr):
"""Проверяет массив байт на наличие сообщения и метаданных."""
try:
hash_from_byte_arr = special_byte_arr[-36:-4].decode("UTF-8")
encoded_text = special_byte_arr[:-36].decode("UTF-8")
decoded_text = Crypter.decode_text(encoded_text)
hash_of_decoded_text = Crypter.get_MD5_hash(decoded_text)
return hash_of_decoded_text == hash_from_byte_arr
except UnicodeDecodeError:
raise Exception(strings.DATA_CORRUPTED)
def make_test_backward_compatibility(self, text):
text_for_code = text
encoded_text = Crypter.encode_text(text_for_code)
decoded_text = Crypter.decode_text(encoded_text)
self.assertEqual(text_for_code, decoded_text)
