Mobile 基础android

wget https://adworld.xctf.org.cn/media/file/task/6a0484a135bb44ba8fdcf829b5d9865b.apk
jadx 6a0484a135bb44ba8fdcf829b5d9865b.apk

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.example.test.ctf02" platformBuildVersionCode="24" platformBuildVersionName="7">
    <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="24"/>
    <application android:theme="@style/AppTheme" android:label="@string/app_name" android:icon="@mipmap/ic_launcher" android:debuggable="true" android:allowBackup="true" android:supportsRtl="true">
        <activity android:name="com.example.test.ctf02.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <receiver android:name="com.example.test.ctf02.GetAndChange" android:enabled="true" android:exported="true">
            <intent-filter>
                <action android:name="android.is.very.fun"/>
            </intent-filter>
        </receiver>
        <activity android:name="com.example.test.ctf02.NextContent"/>
        <activity android:name="com.example.test.ctf02.MainActivity2"/>
    </application>
</manifest>

    @Override // android.support.v7.app.AppCompatActivity, android.support.v4.app.FragmentActivity, android.support.v4.app.BaseFragmentActivityGingerbread, android.app.Activity
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.acticity_main_1);
        this.passWord = (EditText) findViewById(R.id.passWord);
        this.login = (Button) findViewById(R.id.button);
        this.login.setOnClickListener(new View.OnClickListener() { // from class: com.example.test.ctf02.MainActivity.1
            @Override // android.view.View.OnClickListener
            public void onClick(View v) {
                String str = MainActivity.this.passWord.getText().toString();
                Check check = new Check();
                if (check.checkPassword(str)) {
                    Toast.makeText(MainActivity.this, "Good,Please go on!", 0).show();
                    Intent intent = new Intent(MainActivity.this, MainActivity2.class);
                    MainActivity.this.startActivity(intent);
                    MainActivity.this.finish();
                    return;
                }
                Toast.makeText(MainActivity.this, "Failed", 0).show();
            }
        });
    }   

package com.example.test.ctf02;                                                                                                                                                                            
/* loaded from: classes.dex */
public class Check {
    public boolean checkPassword(String str) {
        char[] pass = str.toCharArray();
        if (pass.length != 12) {
            return false;
        }
        for (int len = 0; len < pass.length; len++) {
            pass[len] = (char) (((255 - len) - 100) - pass[len]);
            if (pass[len] != '0' || len >= 12) {
                return false;
            }
        }
        return true;
    }   
}

pwd=[]
plen = 12
for i in range(plen):
   pwd.append( ( (255 - i) - 100) - ord('0'))
print(bytes(pwd))  # b'kjihgfedcba`'

    @Override // android.support.v7.app.AppCompatActivity, android.support.v4.app.FragmentActivity, android.support.v4.app.BaseFragmentActivityGingerbread, android.app.Activity
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_2);
        init();
        this.button.setOnClickListener(new View.OnClickListener() { // from class: com.example.test.ctf02.MainActivity2.1
            @Override // android.view.View.OnClickListener
            public void onClick(View v) {
                String str = MainActivity2.this.editText.getText().toString();
                Intent intent = new Intent(str);
                MainActivity2.this.sendBroadcast(intent);
            }
        });
    }   

    public void init() {
        this.imageView = (ImageView) findViewById(R.id.image);
        this.imageView.setImageResource(R.drawable.timg);
        this.editText = (EditText) findViewById(R.id.pwd);
        this.button = (Button) findViewById(R.id.button);
    }  

public class GetAndChange extends BroadcastReceiver {
    @Override // android.content.BroadcastReceiver
    public void onReceive(Context context, Intent intent) {
        Intent intent1 = new Intent(context, NextContent.class);
        context.startActivity(intent1);
    }   
}

public class NextContent extends AppCompatActivity {
    ImageView imageView;

    /* JADX INFO: Access modifiers changed from: protected */
    @Override // android.support.v7.app.AppCompatActivity, android.support.v4.app.FragmentActivity, android.support.v4.app.BaseFragmentActivityGingerbread, android.app.Activity
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_next_content);
        init(); 
        Change();
    }   

    public void init() {
        this.imageView = (ImageView) findViewById(R.id.imageview);
    }

    public void Change() {
        String strFile = getApplicationContext().getDatabasePath("img.jpg").getAbsolutePath();
        try {   
            File f = new File(strFile);
            if (f.exists()) {
                f.delete();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            InputStream is = getApplicationContext().getResources().getAssets().open("timg_2.zip");
            FileOutputStream fos = new FileOutputStream(strFile);
            byte[] buffer = new byte[1024];
            while (true) {
                int count = is.read(buffer);
                if (count <= 0) {
                    break;
                }
                fos.write(buffer, 0, count);
            }
            fos.flush();
            fos.close();
            is.close();
        } catch (Exception e2) {
            e2.printStackTrace();
        }
        this.imageView.setImageBitmap(BitmapFactory.decodeFile(strFile));
    }
}

$ file ./resources/assets/timg_2.zip
./resources/assets/timg_2.zip: JPEG image data, JFIF standard 1.01, resolution (DPI), density 96x96, segment length 16, baseline, precision 8, 1200x1685, components 3