jeb打开apk

一眼就能看出来，没啥难度，这个难度还不如上一个难度4的题。

直接还原即可

 public static void main(String[] args) throws NoSuchAlgorithmException {String userName = "Tenshine";MessageDigest messageDigest0 = MessageDigest.getInstance("MD5");messageDigest0.reset();messageDigest0.update(userName.getBytes());String s2 = toHexString(messageDigest0.digest(), "");StringBuilder sb = new StringBuilder();int i;for(i = 0; i < s2.length(); i += 2) {sb.append(((char)s2.charAt(i)));}System.out.println(sb);}private static String toHexString(byte[] bytes, String separator) {StringBuilder hexString = new StringBuilder();int i$;for(i$ = 0; i$ < bytes.length; ++i$) {String s1 = Integer.toHexString(bytes[i$] & 0xFF);if(s1.length() == 1) {hexString.append('0');}hexString.append(s1).append(separator);}return hexString.toString();}

运行结果：bc72f242a6af3857
即是flag。