feat(app): hide and obfuscate license checking codes as much as we can

Signed-off-by: YuutaW <17158086+Trumeet@users.noreply.github.com>

12 files changed, 119 insertions, 50 deletions

diff --git a/app/src/main/java/moe/yuuta/ext/ConnCallback.java b/app/src/main/java/moe/yuuta/ext/ConnCallback.java
new file mode 100644
index 0000000..13af66d
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/ext/ConnCallback.java
@@ -0,0 +1,9 @@
+package moe.yuuta.ext;
+
+import android.content.ComponentName;
+import android.os.IBinder;
+
+public interface ConnCallback {
+    void onServiceConnected(ComponentName name, IBinder service);
+    void onServiceDisconnected(ComponentName name);
+}
diff --git a/app/src/main/java/moe/yuuta/ext/IPCResultListener.java b/app/src/main/java/moe/yuuta/ext/IPCResultListener.java
new file mode 100644
index 0000000..bf0045b
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/ext/IPCResultListener.java
@@ -0,0 +1,15 @@
+package moe.yuuta.ext;
+
+public class IPCResultListener extends IResultListener.Stub {
+    private final ResultCallback mCallback;
+
+    public IPCResultListener(ResultCallback mCallback) {
+        this.mCallback = mCallback;
+    }
+
+    @Override
+    public void exec(final int responseCode, final String signedData,
+                     final String signature) {
+        mCallback.verifyLicense(responseCode, signedData, signature);
+    }
+}
diff --git a/app/src/main/java/moe/yuuta/gplicense/ipc/ILicenseResultListener.java b/app/src/main/java/moe/yuuta/ext/IResultListener.java
index a7683b6..706b34a 100644
--- a/app/src/main/java/moe/yuuta/gplicense/ipc/ILicenseResultListener.java
+++ b/app/src/main/java/moe/yuuta/ext/IResultListener.java
@@ -1,4 +1,4 @@
-package moe.yuuta.gplicense.ipc;
+package moe.yuuta.ext;
 
 import android.os.Binder;
 import android.os.IBinder;
@@ -11,8 +11,8 @@ import androidx.annotation.NonNull;
 import moe.yuuta.gplicense.util.Base64;
 import moe.yuuta.gplicense.util.Base64DecoderException;
 
-public interface ILicenseResultListener extends IInterface {
-    abstract class Stub extends Binder implements ILicenseResultListener {
+public interface IResultListener extends IInterface {
+    abstract class Stub extends Binder implements IResultListener {
         private static final String DESCRIPTOR;
 
         static {
@@ -30,13 +30,13 @@ public interface ILicenseResultListener extends IInterface {
             this.attachInterface(this, DESCRIPTOR);
         }
 
-        static ILicenseResultListener asInterface(IBinder obj) {
+        static IResultListener asInterface(IBinder obj) {
             if ((obj == null)) {
                 return null;
             }
             IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
-            if (iin instanceof ILicenseResultListener) {
-                return (ILicenseResultListener) iin;
+            if (iin instanceof IResultListener) {
+                return (IResultListener) iin;
             }
             return new Stub.Proxy(obj);
         }
@@ -53,12 +53,12 @@ public interface ILicenseResultListener extends IInterface {
                     reply.writeString(DESCRIPTOR);
                     return true;
                 }
-                case TRANSACTION_verifyLicense: {
+                case TRANSACTION: {
                     data.enforceInterface(DESCRIPTOR);
                     int responseCode = data.readInt();
                     String signedData = data.readString();
                     String signature = data.readString();
-                    this.verifyLicense(responseCode, signedData, signature);
+                    this.exec(responseCode, signedData, signature);
                     return true;
                 }
                 default: {
@@ -67,7 +67,7 @@ public interface ILicenseResultListener extends IInterface {
             }
         }
 
-        private static class Proxy implements ILicenseResultListener {
+        private static class Proxy implements IResultListener {
             private IBinder mRemote;
 
             Proxy(IBinder remote) {
@@ -80,22 +80,23 @@ public interface ILicenseResultListener extends IInterface {
             }
 
             @Override
-            public void verifyLicense(int responseCode, String signedData, String signature) throws RemoteException {
+            public void exec(int responseCode, String signedData, String signature) throws RemoteException {
                 Parcel args = Parcel.obtain();
                 try {
                     args.writeInterfaceToken(DESCRIPTOR);
                     args.writeInt(responseCode);
                     args.writeString(signedData);
                     args.writeString(signature);
-                    mRemote.transact(TRANSACTION_verifyLicense, args, null, IBinder.FLAG_ONEWAY);
+                    mRemote.transact(TRANSACTION, args, null, IBinder.FLAG_ONEWAY);
                 } finally {
                     args.recycle();
                 }
             }
         }
 
-        static final int TRANSACTION_verifyLicense = IBinder.FIRST_CALL_TRANSACTION;
+        static final int TRANSACTION = IBinder.FIRST_CALL_TRANSACTION;
     }
 
-    void verifyLicense(int responseCode, String signedData, String signature) throws RemoteException;
+    // verifyLicense
+    void exec(int responseCode, String signedData, String signature) throws RemoteException;
 }
\ No newline at end of file
diff --git a/app/src/main/java/moe/yuuta/gplicense/ipc/ILicensingService.java b/app/src/main/java/moe/yuuta/ext/IService.java
index 14e27f4..ea0b136 100644
--- a/app/src/main/java/moe/yuuta/gplicense/ipc/ILicensingService.java
+++ b/app/src/main/java/moe/yuuta/ext/IService.java
@@ -1,4 +1,4 @@
-package moe.yuuta.gplicense.ipc;
+package moe.yuuta.ext;
 
 import android.os.Binder;
 import android.os.IBinder;
@@ -11,8 +11,8 @@ import androidx.annotation.NonNull;
 import moe.yuuta.gplicense.util.Base64;
 import moe.yuuta.gplicense.util.Base64DecoderException;
 
-public interface ILicensingService extends IInterface {
-    abstract class Stub extends Binder implements ILicensingService {
+public interface IService extends IInterface {
+    abstract class Stub extends Binder implements IService {
         private static final String DESCRIPTOR;
 
         static {
@@ -30,15 +30,15 @@ public interface ILicensingService extends IInterface {
             this.attachInterface(this, DESCRIPTOR);
         }
 
-        public static ILicensingService asInterface(IBinder obj) {
+        public static IService asInterface(IBinder obj) {
             if ((obj == null)) {
                 return null;
             }
             IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
-            if (iin instanceof ILicensingService) {
-                return (ILicensingService) iin;
+            if (iin instanceof IService) {
+                return (IService) iin;
             }
-            return new ILicensingService.Stub.Proxy(obj);
+            return new IService.Stub.Proxy(obj);
         }
 
         @Override
@@ -57,8 +57,8 @@ public interface ILicensingService extends IInterface {
                     data.enforceInterface(DESCRIPTOR);
                     long nonce = data.readLong();
                     String packageName = data.readString();
-                    ILicenseResultListener listener = ILicenseResultListener.Stub.asInterface(data.readStrongBinder());
-                    this.checkLicense(nonce, packageName, listener);
+                    IResultListener listener = IResultListener.Stub.asInterface(data.readStrongBinder());
+                    this.exec(nonce, packageName, listener);
                     return true;
                 }
                 default: {
@@ -67,7 +67,7 @@ public interface ILicensingService extends IInterface {
             }
         }
 
-        private static class Proxy implements ILicensingService {
+        private static class Proxy implements IService {
             private IBinder mRemote;
 
             Proxy(IBinder remote) {
@@ -80,7 +80,7 @@ public interface ILicensingService extends IInterface {
             }
             
             @Override
-            public void checkLicense(long nonce, String packageName, ILicenseResultListener listener) throws RemoteException {
+            public void exec(long nonce, String packageName, IResultListener listener) throws RemoteException {
                 Parcel args = Parcel.obtain();
                 try {
                     args.writeInterfaceToken(DESCRIPTOR);
@@ -97,5 +97,6 @@ public interface ILicensingService extends IInterface {
         static final int TRANSACTION_checkLicense = IBinder.FIRST_CALL_TRANSACTION;
     }
 
-    void checkLicense(long nonce, String packageName, ILicenseResultListener listener) throws RemoteException;
+    // checkLicense
+    void exec(long nonce, String packageName, IResultListener listener) throws RemoteException;
 }
\ No newline at end of file
diff --git a/app/src/main/java/moe/yuuta/ext/LicServiceConn.java b/app/src/main/java/moe/yuuta/ext/LicServiceConn.java
new file mode 100644
index 0000000..f0ad766
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/ext/LicServiceConn.java
@@ -0,0 +1,23 @@
+package moe.yuuta.ext;
+
+import android.content.ComponentName;
+import android.content.ServiceConnection;
+import android.os.IBinder;
+
+public class LicServiceConn implements ServiceConnection {
+    private final ConnCallback mCallback;
+
+    public LicServiceConn(ConnCallback mCallback) {
+        this.mCallback = mCallback;
+    }
+
+    @Override
+    public synchronized void onServiceConnected(ComponentName name, IBinder service) {
+        mCallback.onServiceConnected(name, service);
+    }
+
+    @Override
+    public synchronized void onServiceDisconnected(ComponentName name) {
+        mCallback.onServiceDisconnected(name);
+    }
+}
diff --git a/app/src/main/java/moe/yuuta/ext/ResultCallback.java b/app/src/main/java/moe/yuuta/ext/ResultCallback.java
new file mode 100644
index 0000000..4feafba
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/ext/ResultCallback.java
@@ -0,0 +1,6 @@
+package moe.yuuta.ext;
+
+public interface ResultCallback {
+    void verifyLicense(final int responseCode, final String signedData,
+                       final String signature);
+}
diff --git a/app/src/main/java/moe/yuuta/ext/package-info.java b/app/src/main/java/moe/yuuta/ext/package-info.java
new file mode 100644
index 0000000..128e042
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/ext/package-info.java
@@ -0,0 +1,4 @@
+/**
+ * Classes which cannot be processed by ProGuard are moved to here to keep LicenseChecker processed.
+ */
+package moe.yuuta.ext;
\ No newline at end of file
diff --git a/app/src/main/java/moe/yuuta/gplicense/LicenseChecker.java b/app/src/main/java/moe/yuuta/gplicense/LicenseChecker.java
index 92986b8..7d4cfa8 100644
--- a/app/src/main/java/moe/yuuta/gplicense/LicenseChecker.java
+++ b/app/src/main/java/moe/yuuta/gplicense/LicenseChecker.java
@@ -4,7 +4,6 @@ import android.annotation.SuppressLint;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
-import android.content.ServiceConnection;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.Handler;
 import android.os.HandlerThread;
@@ -27,8 +26,11 @@ import java.util.LinkedList;
 import java.util.Queue;
 import java.util.Set;
 
-import moe.yuuta.gplicense.ipc.ILicenseResultListener;
-import moe.yuuta.gplicense.ipc.ILicensingService;
+import moe.yuuta.ext.ConnCallback;
+import moe.yuuta.ext.IPCResultListener;
+import moe.yuuta.ext.IService;
+import moe.yuuta.ext.LicServiceConn;
+import moe.yuuta.ext.ResultCallback;
 import moe.yuuta.gplicense.util.Base64;
 import moe.yuuta.gplicense.util.Base64DecoderException;
 import moe.yuuta.workmode.BuildConfig;
@@ -44,7 +46,7 @@ import moe.yuuta.workmode.BuildConfig;
  * Must also provide the Base64-encoded RSA public key associated with your developer account. The
  * public key is obtainable from the publisher site.
  */
-public class LicenseChecker implements ServiceConnection {
+public class LicenseChecker implements ConnCallback {
     private static final Logger logger = XLog.tag("LCK").build();
 
     private static final String KEY_FACTORY_ALGORITHM = "RSA";
@@ -55,7 +57,7 @@ public class LicenseChecker implements ServiceConnection {
     private static final SecureRandom RANDOM = new SecureRandom();
     private static final boolean DEBUG_LICENSE_ERROR = BuildConfig.DEBUG;
 
-    private ILicensingService mService;
+    private IService mService;
 
     private PublicKey mPublicKey;
     private final Context mContext;
@@ -70,6 +72,8 @@ public class LicenseChecker implements ServiceConnection {
     private final Set<LicenseValidator> mChecksInProgress = new HashSet<LicenseValidator>();
     private final Queue<LicenseValidator> mPendingChecks = new LinkedList<LicenseValidator>();
 
+    private LicServiceConn mConn;
+
     /**
      * @param context a Context
      * @param policy implementation of Policy
@@ -118,7 +122,7 @@ public class LicenseChecker implements ServiceConnection {
      * recommend obfuscating the string that is passed into bindService using another method of your
      * own devising.
      * <p>
-     * source string: "com.android.vending.licensing.ILicensingService"
+     * source string: "com.android.vending.licensing.IService"
      * <p>
      *
      * @param callback
@@ -127,7 +131,7 @@ public class LicenseChecker implements ServiceConnection {
         // If we have a valid recent LICENSED response, we can skip asking
         // Market.
         if (mPolicy.allowAccess()) {
-            logger.i("Using cached license response");
+            logger.i("Using cached response");
             callback.allow(Policy.LICENSED);
         } else {
             LicenseValidator validator = new LicenseValidator(mPolicy, new NullDeviceLimiter(),
@@ -136,12 +140,13 @@ public class LicenseChecker implements ServiceConnection {
             if (mService == null) {
                 logger.i("Binding to service.");
                 try {
+                    mConn = new LicServiceConn(this);
                     boolean bindResult = mContext
                             .bindService(
                                     new Intent(
                                             new String(
                                                     // Base64 encoded -
-                                                    // com.android.vending.licensing.ILicensingService
+                                                    // com.android.vending.licensing.IService
                                                     // Consider encoding this in another way in your
                                                     // code to improve security
                                                     Base64.decode(
@@ -163,7 +168,7 @@ public class LicenseChecker implements ServiceConnection {
                                                             // com.android.vending
                                                             Base64.decode(
                                                                     "Y29tLmFuZHJvaWQudmVuZGluZw=="))),
-                                    this, // ServiceConnection.
+                                    mConn, // ServiceConnection.
                                     Context.BIND_AUTO_CREATE);
                     if (bindResult) {
                         mPendingChecks.offer(validator);
@@ -188,12 +193,12 @@ public class LicenseChecker implements ServiceConnection {
         while ((validator = mPendingChecks.poll()) != null) {
             try {
                 logger.i("Executing on service for " + validator.getPackageName());
-                mService.checkLicense(
+                mService.exec(
                         validator.getNonce(), validator.getPackageName(),
-                        new ResultListener(validator));
+                        new IPCResultListener(new ResultListener(validator)));
                 mChecksInProgress.add(validator);
             } catch (RemoteException e) {
-                logger.w("RemoteException in checkLicense call.", e);
+                logger.w("RemoteException in exec call.", e);
                 handleServiceConnectionError(validator);
             }
         }
@@ -206,7 +211,7 @@ public class LicenseChecker implements ServiceConnection {
         }
     }
 
-    private class ResultListener extends ILicenseResultListener.Stub {
+    private class ResultListener implements ResultCallback {
         private final LicenseValidator mValidator;
         private Runnable mOnTimeout;
 
@@ -226,6 +231,7 @@ public class LicenseChecker implements ServiceConnection {
 
         // Runs in IPC thread pool. Post it to the Handler, so we can guarantee
         // either this or the timeout runs.
+        @Override
         public void verifyLicense(final int responseCode, final String signedData,
                                   final String signature) {
             mHandler.post(() -> {
@@ -280,11 +286,13 @@ public class LicenseChecker implements ServiceConnection {
         }
     }
 
+    @Override
     public synchronized void onServiceConnected(ComponentName name, IBinder service) {
-        mService = ILicensingService.Stub.asInterface(service);
+        mService = IService.Stub.asInterface(service);
         runChecks();
     }
 
+    @Override
     public synchronized void onServiceDisconnected(ComponentName name) {
         // Called when the connection with the service has been
         // unexpectedly disconnected. That is, Market crashed.
@@ -311,7 +319,7 @@ public class LicenseChecker implements ServiceConnection {
     private void cleanupService() {
         if (mService != null) {
             try {
-                mContext.unbindService(this);
+                mContext.unbindService(mConn);
             } catch (IllegalArgumentException e) {
                 // Somehow we've already been unbound. This is a non-fatal
                 // error.
diff --git a/app/src/main/java/moe/yuuta/gplicense/LicenseValidator.java b/app/src/main/java/moe/yuuta/gplicense/LicenseValidator.java
index 142f350..d34d614 100644
--- a/app/src/main/java/moe/yuuta/gplicense/LicenseValidator.java
+++ b/app/src/main/java/moe/yuuta/gplicense/LicenseValidator.java
@@ -184,7 +184,7 @@ class LicenseValidator {
                 handleApplicationError(LicenseCheckerCallback.ERROR_NOT_MARKET_MANAGED);
                 break;
             default:
-                logger.e("Unknown response code for license check.");
+                logger.e("Unknown response code for checking.");
                 handleInvalidResponse();
         }
     }
diff --git a/app/src/main/java/moe/yuuta/gplicense/ServerManagedPolicy.java b/app/src/main/java/moe/yuuta/gplicense/ServerManagedPolicy.java
index 8355cb8..fcc3451 100644
--- a/app/src/main/java/moe/yuuta/gplicense/ServerManagedPolicy.java
+++ b/app/src/main/java/moe/yuuta/gplicense/ServerManagedPolicy.java
@@ -159,7 +159,7 @@ public class ServerManagedPolicy implements Policy {
             lValidityTimestamp = Long.parseLong(validityTimestamp);
         } catch (NumberFormatException e) {
             // No response or not parsable, expire in one minute.
-            logger.w("License validity timestamp (VT) missing, caching for a minute");
+            logger.w("Validity timestamp (VT) missing, caching for a minute");
             lValidityTimestamp = System.currentTimeMillis() + MILLIS_PER_MINUTE;
             validityTimestamp = Long.toString(lValidityTimestamp);
         }
diff --git a/app/src/main/java/moe/yuuta/workmode/MainActivity.kt b/app/src/main/java/moe/yuuta/workmode/MainActivity.kt
index b09e38e..792e948 100644
--- a/app/src/main/java/moe/yuuta/workmode/MainActivity.kt
+++ b/app/src/main/java/moe/yuuta/workmode/MainActivity.kt
@@ -29,7 +29,7 @@ import moe.yuuta.gplicense.LicenseCheckerCallback
 import moe.yuuta.gplicense.Policy
 import moe.yuuta.workmode.access.AccessorStarter
 import moe.yuuta.workmode.async.*
-import moe.yuuta.workmode.gpl.GPLicenser
+import moe.yuuta.workmode.gpl.GPL
 import moe.yuuta.workmode.suspend.AsyncSuspender
 import moe.yuuta.workmode.suspend.SuspendTile
 import moe.yuuta.workmode.suspend.data.ListMode
@@ -78,7 +78,7 @@ class MainActivity : AppCompatActivity(), SwitchBar.OnSwitchChangeListener, View
         filter.addAction(AccessorStarter.ACTION_UPDATE_UI_PROGRESS)
         registerReceiver(mUIUpdateReceiver, filter)
         scheduleUpdateChecking()
-        lifecycle.addObserver(GPLicenser(this, lifecycle, this))
+        lifecycle.addObserver(GPL(this, lifecycle, this))
         setProgressUI(false)
     }
 
diff --git a/app/src/main/java/moe/yuuta/workmode/gpl/GPLicenser.kt b/app/src/main/java/moe/yuuta/workmode/gpl/GPL.kt
index fdcad9a..3824f19 100644
--- a/app/src/main/java/moe/yuuta/workmode/gpl/GPLicenser.kt
+++ b/app/src/main/java/moe/yuuta/workmode/gpl/GPL.kt
@@ -12,7 +12,9 @@ import moe.yuuta.gplicense.LicenseCheckerCallback
 import moe.yuuta.gplicense.ServerManagedPolicy
 import moe.yuuta.workmode.BuildConfig
 
-class GPLicenser(
+// #Anti-Crack
+// Google Play Licenser
+class GPL(
         private val context: Context,
         private val lifecycle: Lifecycle,
         private val callback: LicenseCheckerCallback
@@ -22,24 +24,24 @@ class GPLicenser(
             -9, -5, -77, -71, -36, -79, -11, 37, -69, 88
     )
 
-    private lateinit var checker: LicenseChecker
+    private lateinit var instance: LicenseChecker
 
     @OnLifecycleEvent(Lifecycle.Event.ON_CREATE)
     fun start() {
         @SuppressLint("HardwareIds") val android_id = Settings.Secure.getString(context.contentResolver,
                 Settings.Secure.ANDROID_ID)
-        checker = LicenseChecker(
+        instance = LicenseChecker(
                 context,
                 ServerManagedPolicy(context, AESObfuscator(SALT, BuildConfig.APPLICATION_ID, android_id)),
                 BuildConfig.GOOGLE_PLAY_LICENSING_KEY
         )
-        checker.checkAccess(callback)
+        instance.checkAccess(callback)
     }
 
     @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
     fun destroy() {
-        if (::checker.isInitialized) {
-            checker.onDestroy()
+        if (::instance.isInitialized) {
+            instance.onDestroy()
         }
     }
 }
\ No newline at end of file