Store 3DES in String instead of CipherOutputStream

Question

I'm trying to 3DES encrypt a string and store it in a properties file using this example. The problem I'm having is I do not want to write the contents of encrypt() and decrypt() to a file directly from the methods. I want to store it in a string for use later.

Below are the methods I'm using.

As you can see this uses CipherOutputStream and CipherInputStream. How would I read the result of both encrypt() and decrypt() into a String instead of writing it out to file?

  public static void encrypt(SecretKey key, InputStream in, OutputStream out)
      throws NoSuchAlgorithmException, InvalidKeyException,
      NoSuchPaddingException, IOException {
    // Create and initialize the encryption engine
    Cipher cipher = Cipher.getInstance("DESede");
    cipher.init(Cipher.ENCRYPT_MODE, key);

    // Create a special output stream to do the work for us
    CipherOutputStream cos = new CipherOutputStream(out, cipher);

    // Read from the input and write to the encrypting output stream
    byte[] buffer = new byte[2048];
    int bytesRead;
    while ((bytesRead = in.read(buffer)) != -1) {
      cos.write(buffer, 0, bytesRead);
    }
    cos.close();

    // For extra security, don't leave any plaintext hanging around memory.
    java.util.Arrays.fill(buffer, (byte) 0);
  }

  /**
   * Use the specified TripleDES key to decrypt bytes ready from the input
   * stream and write them to the output stream. This method uses uses Cipher
   * directly to show how it can be done without CipherInputStream and
   * CipherOutputStream.
   */
  public static void decrypt(SecretKey key, InputStream in, OutputStream out)
      throws NoSuchAlgorithmException, InvalidKeyException, IOException,
      IllegalBlockSizeException, NoSuchPaddingException,
      BadPaddingException {
    // Create and initialize the decryption engine
    Cipher cipher = Cipher.getInstance("DESede");
    cipher.init(Cipher.DECRYPT_MODE, key);

    // Read bytes, decrypt, and write them out.
    byte[] buffer = new byte[2048];
    int bytesRead;
    while ((bytesRead = in.read(buffer)) != -1) {
      out.write(cipher.update(buffer, 0, bytesRead));
    }

    // Write out the final bunch of decrypted bytes
    out.write(cipher.doFinal());
    out.flush();
  }

Answer 1

Simple: instead of passing a file output stream to these methods - pass a different kind of stream, for example a ByteArrayOutputStream.

Then you can extract the encrypted data as string from that stream.

And to ensure that the final result is reasonable encoded, you should actually use some kind of Base64OutputStream which in turn writes to that ByteArrayOutputStream.