code: def EncryptPrivateKey(self, decrypted):
          
          aes = AES.new(self._master_key, AES.MODE_CBC, self._iv)
          return aes.encrypt(decrypted)
docs: Encrypt the provided plaintext with the initialized private key.
  
          Args:
              decrypted (byte string): the plaintext to be encrypted.
  
          Returns:
              bytes: the ciphertext.