docs: public byte[] generateSecretKey() throws AESException {
          try {
              // Get the KeyGenerator
              KeyGenerator kgen = KeyGenerator.getInstance(ENCRYPTION_ALGORITHM);
              kgen.init(KEY_SIZE); // 192 and 256 bits may not be available
              // Generate the secret key specs.
              SecretKey skey = kgen.generateKey();
              secretKey = skey.getEncoded();
              return secretKey;
          } catch (NoSuchAlgorithmException e) {
              throw new AESException(e);
          }
      }