// Process AAD (not included in output)
        cipher.processAADBytes(associatedData, 0, associatedData.length);

        // Process message (will be encrypted)
        final byte[] output = new byte[cipher.getOutputSize(message.length)];
        int len = cipher.processBytes(message, 0, message.length, output, 0);
        len += cipher.doFinal(output, len);

        // Split ciphertext and authentication tag