code: import javax.crypto.Cipher;
  
  import net.sourceforge.stripes.util.Base64;
  
  class EnsureNonEmptyInput {
    String pattern(byte[] inbytes, int index, int DISCARD_BYTES, int BASE64_OPTIONS) throws Exception {
      Cipher cipher = getCipher(Cipher.ENCRYPT_MODE);
      int inputLength = inbytes.length;
      int size = cipher.getOutputSize(DISCARD_BYTES + inputLength);
      byte[] output = new byte[size];
      if (inbytes.length == 0) {
        cipher.doFinal(output, index);
      } else {
        cipher.doFinal(inbytes, 0, inbytes.length, output, index);
      }
      return Base64.encodeBytes(output, BASE64_OPTIONS);
    }
  }