code: public static String base64dec(String str) {
  		if (str == null) {
  			return "";
  		}
  		try {
  			return new String(Base64.decodeBase64(str), Config.DEFAULT_ENCODING);
  		} catch (UnsupportedEncodingException ex) {
  			return "";
  		}
  	}
docs: Decodes a string from Base64.
  @param str the encoded string
  @return a decoded string