private void saveSecretKey(String ksAlias, ObjectOutputStream oos, KeyStore.SecretKeyEntry entry) throws IOException, GeneralSecurityException {
            ByteArrayOutputStream entryData = new ByteArrayOutputStream(1024);
            ObjectOutputStream entryOos = new ObjectOutputStream(entryData);
            entryOos.writeUTF(ksAlias);
            writeBytes(entry.getSecretKey().getEncoded(), entryOos);
            entryOos.flush();

            encrypt.init(Cipher.ENCRYPT_MODE, storageSecretKey);
            int blockSize = encrypt.getBlockSize();
            Assert.checkMaximumParameter("cipher block size", 256, blockSize);
            byte[] padded = pkcs7Pad(entryData.toByteArray(), blockSize);

            byte[] encrypted = encrypt.doFinal(padded);
            byte[] iv = encrypt.getIV();

            oos.writeInt(SECRET_KEY_ENTRY_TYPE);
            writeBytes(encrypted, oos);
            writeBytes(iv, oos);
        }