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1package derp.derp;
2
3import android.os.Bundle;
4import android.support.v7.app.AppCompatActivity;
5import android.util.Base64;
6import android.util.Log;
7import java.io.UnsupportedEncodingException;
8import java.security.InvalidKeyException;
9import java.security.NoSuchAlgorithmException;
10import java.security.spec.InvalidKeySpecException;
11import javax.crypto.BadPaddingException;
12import javax.crypto.Cipher;
13import javax.crypto.IllegalBlockSizeException;
14import javax.crypto.NoSuchPaddingException;
15import javax.crypto.SecretKey;
16import javax.crypto.SecretKeyFactory;
17import javax.crypto.spec.DESKeySpec;
18
19public class MainActivity extends AppCompatActivity {
20    protected String obvious_flag = "Overdrive2018: You find some flag, congratulations!";
21    protected String part_1 = "T3ZlcmRyaXZlMjAxOA==";
22    protected String part_2 = "vfIrelpbby";
23    protected String part_3 = "5GEHDq0Xajujbs+9J6oMOw==";
24
25    protected String crypto_1(String coolCrypto, int shift) {
26        String s = "";
27        int len = coolCrypto.length();
28        for (int x = 0; x < len; x++) {
29            if (((char) (coolCrypto.charAt(x) + shift)) > 'z') {
30                s = s + ((char) (coolCrypto.charAt(x) - (26 - shift)));
31            } else {
32                s = s + ((char) (coolCrypto.charAt(x) + shift));
33            }
34        }
35        return s;
36    }
37
38    protected String crypto_2(String coolCrypto) {
39        byte[] valueDecoded = new byte[0];
40        try {
41            valueDecoded = Base64.decode(coolCrypto.getBytes("UTF-8"), 0);
42        } catch (UnsupportedEncodingException e) {
43            e.printStackTrace();
44        }
45        return new String(valueDecoded);
46    }
47
48    protected String crypto_3(String coolCrypto) {
49        byte[] valueDecoded = new byte[0];
50        try {
51            SecretKey key = SecretKeyFactory.getInstance("DES").generateSecret(new DESKeySpec("VerySecureKey11".getBytes()));
52            Cipher cipher = Cipher.getInstance("DES");
53            cipher.init(1, key);
54            valueDecoded = cipher.doFinal(crypto_2(coolCrypto).getBytes());
55        } catch (NoSuchAlgorithmException e) {
56            e.printStackTrace();
57            return "1";
58        } catch (InvalidKeyException e2) {
59            e2.printStackTrace();
60            return "2";
61        } catch (NoSuchPaddingException e3) {
62            e3.printStackTrace();
63            return "3";
64        } catch (BadPaddingException e4) {
65            e4.printStackTrace();
66            return "4";
67        } catch (IllegalBlockSizeException e5) {
68            e5.printStackTrace();
69            return "6";
70        } catch (InvalidKeySpecException e6) {
71            e6.printStackTrace();
72        }
73        return new String(valueDecoded);
74    }
75
76    protected void onCreate(Bundle savedInstanceState) {
77        super.onCreate(savedInstanceState);
78        Log.d("DERP", "No easy solution for you :0");
79        String flag = crypto_1(this.part_2, 13) + crypto_2(this.part_1) + crypto_3(this.part_3);
80    }
81}