KCTF2019 变形金刚

变形金刚"/>

KCTF2019 变形金刚

一道安卓逆向，由于没找到关键函数，比赛时没搞出来，复现一下

对APK进行反编译，结果十分诡异，看起来就像是对用户名进行了字符串反转，但测试后并非这样

public class MainActivity extends AppCompiatActivity {class MyHandler extends Handler {WeakReference mWeakReference;public MyHandler(MainActivity arg2) {super();this.mWeakReference = new WeakReference(arg2);}public void handleMessage(Message arg6) {String v6_1;StringBuilder v1;super.handleMessage(arg6);Object v0 = this.mWeakReference.get();if(v0 == null) {return;}switch(arg6.what) {case 0: {Object v6 = arg6.obj;if(!TextUtils.isEmpty(((CharSequence)v6))) {v1 = new StringBuilder();int v3;for(v3 = 0; v3 < ((String)v6).length() / 2; ++v3) {v1.append(((String)v6).charAt(v3));}v6_1 = v1.toString();}v1 = new StringBuilder();v1.append("flag{");v1.append(v6_1);v1.append("}");Toast.makeText(((Context)v0), v1.toString(), 1).show();break;}case 1: {Toast.makeText(((Context)v0), "登录失败", 1).show();break;}default: {break;}}((MainActivity)v0).login.setEnabled(true);}}private void login(String arg3, String arg4, Handler arg5) {Toast.makeText(((Context)this), "登录中。。。", 1).show();MainActivity.runnable = new Runnable(arg4, arg3, arg5) {public void run() {Message v0 = Message.obtain();StringBuilder v1 = new StringBuilder(this.val$password);if(this.val$name.equals(v1.reverse().toString())) {v0.obj = v1.toString();}else {v0.what = 1;}this.val$handler.sendMessage(v0);}};MainActivity.cachedThreadPool.execute(MainActivity.runnable);}protected void onCreate(Bundle arg2) {super.onCreate(arg2);this.setContentView(2131296283);this.login = this.findViewById(2131165260);this.handler = new MyHandler(this);this.login.setOnClickListener(new View$OnClickListener() {public void onClick(View arg4) {MainActivity.this.mName = MainActivity.this.name.getText().toString();MainActivity.this.mPassword = MainActivity.this.password.getText().toString();