Fix a crash on Kitkat. It doesn't like the KeyStoreHandle class for some reason

app/src/main/java/me/impy/aegis/SlotHolder.java

@@ -7,10 +7,12 @@ import android.widget.LinearLayout;
 import android.widget.TextView;
 
 import me.impy.aegis.crypto.KeyStoreHandle;
+import me.impy.aegis.crypto.KeyStoreHandleException;
 import me.impy.aegis.crypto.slots.FingerprintSlot;
 import me.impy.aegis.crypto.slots.PasswordSlot;
 import me.impy.aegis.crypto.slots.RawSlot;
 import me.impy.aegis.crypto.slots.Slot;
+import me.impy.aegis.helpers.FingerprintHelper;
 
 public class SlotHolder extends RecyclerView.ViewHolder {
     private TextView _slotUsed;
@@ -35,12 +37,14 @@ public class SlotHolder extends RecyclerView.ViewHolder {
         } else if (slot instanceof FingerprintSlot) {
             _slotName.setText("Finger");
             _slotImg.setImageResource(R.drawable.ic_fingerprint_black_24dp);
+            if (FingerprintHelper.isSupported()) {
                 try {
                     KeyStoreHandle keyStore = new KeyStoreHandle();
                     if (keyStore.containsKey(slot.getID())) {
                         _slotUsed.setVisibility(View.VISIBLE);
                     }
-            } catch (Exception e) { }
+                } catch (KeyStoreHandleException e) { }
+            }
         } else if (slot instanceof RawSlot) {
             _slotName.setText("Raw");
             _slotImg.setImageResource(R.drawable.ic_vpn_key_black_24dp);

app/src/main/java/me/impy/aegis/SlotManagerActivity.java

@@ -1,6 +1,7 @@
 package me.impy.aegis;
 
 import android.content.Intent;
+import android.os.Build;
 import android.os.Bundle;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AlertDialog;
@@ -9,12 +10,12 @@ import android.support.v7.widget.RecyclerView;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
-import android.widget.EditText;
 import android.widget.Toast;
 
 import javax.crypto.Cipher;
 
 import me.impy.aegis.crypto.KeyStoreHandle;
+import me.impy.aegis.crypto.KeyStoreHandleException;
 import me.impy.aegis.crypto.MasterKey;
 import me.impy.aegis.crypto.slots.FingerprintSlot;
 import me.impy.aegis.crypto.slots.PasswordSlot;
@@ -70,6 +71,7 @@ public class SlotManagerActivity extends AegisActivity implements SlotAdapter.Li
         // only show the fingerprint option if we can get an instance of the fingerprint manager
         // and if none of the slots in the collection has a matching alias in the keystore
         int visibility = View.VISIBLE;
+        if (FingerprintHelper.isSupported()) {
             try {
                 KeyStoreHandle keyStore = new KeyStoreHandle();
                 for (FingerprintSlot slot : _slots.findAll(FingerprintSlot.class)) {
@@ -78,7 +80,10 @@ public class SlotManagerActivity extends AegisActivity implements SlotAdapter.Li
                         break;
                     }
                 }
-        } catch (Exception e) {
+            } catch (KeyStoreHandleException e) {
+                visibility = View.GONE;
+            }
+        } else {
             visibility = View.GONE;
         }
         findViewById(R.id.button_add_fingerprint).setVisibility(visibility);

app/src/main/java/me/impy/aegis/crypto/KeyStoreHandle.java

@@ -19,23 +19,29 @@ import javax.crypto.KeyGenerator;
 import javax.crypto.NoSuchPaddingException;
 import javax.crypto.SecretKey;
 
-import me.impy.aegis.crypto.slots.FingerprintSlot;
-
 public class KeyStoreHandle {
     private final KeyStore _keyStore;
     private static final String STORE_NAME = "AndroidKeyStore";
 
-    public KeyStoreHandle() throws KeyStoreException, CertificateException, NoSuchAlgorithmException, IOException {
+    public KeyStoreHandle() throws KeyStoreHandleException {
+        try {
             _keyStore = KeyStore.getInstance(STORE_NAME);
             _keyStore.load(null);
+        } catch (KeyStoreException | CertificateException | NoSuchAlgorithmException | IOException e) {
+            throw new KeyStoreHandleException(e);
+        }
     }
 
-    public boolean containsKey(String id) throws KeyStoreException {
+    public boolean containsKey(String id) throws KeyStoreHandleException {
+        try {
             return _keyStore.containsAlias(id);
+        } catch (KeyStoreException e) {
+            throw new KeyStoreHandleException(e);
+        }
     }
 
     public SecretKey generateKey(String id) throws Exception {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+        if (isSupported()) {
             KeyGenerator generator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, STORE_NAME);
             generator.init(new KeyGenParameterSpec.Builder(id,
                 KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
@@ -58,7 +64,7 @@ public class KeyStoreHandle {
 
         // try to initialize a dummy cipher
         // and see if KeyPermanentlyInvalidatedException is thrown
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+        if (isSupported()) {
             try {
                 @SuppressLint("GetInstance")
                 Cipher cipher = Cipher.getInstance(CryptoUtils.CRYPTO_CIPHER_RAW);
@@ -76,4 +82,8 @@ public class KeyStoreHandle {
     public void deleteKey(String id) throws KeyStoreException {
         _keyStore.deleteEntry(id);
     }
+
+    public static boolean isSupported() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
+    }
 }

app/src/main/java/me/impy/aegis/crypto/KeyStoreHandleException.java

@@ -0,0 +1,7 @@
+package me.impy.aegis.crypto;
+
+public class KeyStoreHandleException extends Exception {
+    public KeyStoreHandleException(Throwable cause) {
+        super(cause);
+    }
+}

app/src/main/java/me/impy/aegis/helpers/FingerprintHelper.java

@@ -11,14 +11,16 @@ public class FingerprintHelper {
     }
 
     public static FingerprintManager getManager(Context context) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+        if (isSupported() && PermissionHelper.granted(context, Manifest.permission.USE_FINGERPRINT)) {
-            if (PermissionHelper.granted(context, Manifest.permission.USE_FINGERPRINT)) {
             FingerprintManager manager = (FingerprintManager) context.getSystemService(Context.FINGERPRINT_SERVICE);
             if (manager != null && manager.isHardwareDetected() && manager.hasEnrolledFingerprints()) {
                 return manager;
             }
         }
-        }
         return null;
     }
+
+    public static boolean isSupported() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
+    }
 }