Password list get's loaded in the background

- User has to repeat his passphrase
- Passwords can now be toggled
- Error message on wrong passphrase on decryption

app/src/main/AndroidManifest.xml

@@ -12,7 +12,8 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".ViewActivity"></activity>
+        <activity android:name=".GeneratorActivity"></activity>
+        <activity android:name=".ViewActivity" />
         <activity android:name=".PassphraseActivity" />
         <activity
             android:name=".CreateActivity"

app/src/main/java/com/github/mondei1/offpass/CreateActivity.kt

@@ -10,6 +10,8 @@ import android.os.Bundle
 import android.print.PrintAttributes
 import android.print.PrintJob
 import android.print.PrintManager
+import android.text.method.HideReturnsTransformationMethod
+import android.text.method.PasswordTransformationMethod
 import android.util.Base64
 import android.util.Log
 import android.view.ContextThemeWrapper
@@ -27,11 +29,12 @@ import com.google.zxing.integration.android.IntentResult
 import com.journeyapps.barcodescanner.BarcodeEncoder
 import dev.turingcomplete.kotlinonetimepassword.GoogleAuthenticator
 import kotlinx.android.synthetic.main.activity_create.*
-import kotlinx.android.synthetic.main.dialogpassphrase.*
 import kotlinx.android.synthetic.main.dialogpassphrase.view.*
 import kotlinx.coroutines.*
 import java.io.ByteArrayOutputStream
+import java.lang.IllegalArgumentException
 import java.util.*
+import kotlin.collections.ArrayList
 
 class CreateActivity : AppCompatActivity() {
     private var schema: QRSchema? = null
@@ -43,6 +46,8 @@ class CreateActivity : AppCompatActivity() {
 
     private var fa_uri: Uri? = null
 
+    private var known_passwords = ArrayList<String>()
+
     /**
      * Gets triggered when the user clicks on printing button (top left) and renders the paper to
      * print.
@@ -130,17 +135,7 @@ class CreateActivity : AppCompatActivity() {
     }
 
     fun passwordKnown(password: String): Boolean {
-        val known_passwords = String(this.resources.openRawResource(
+        return this.known_passwords.contains(password)
-            this.resources.getIdentifier("passwordlist", "raw", this.packageName)
-        ).readBytes())
-
-        val known_passwords_array = runBlocking {
-            known_passwords.split("\n")
-        }
-
-        Log.i("Create Activity", "Size of passwords: ${known_passwords_array.size}")
-
-        return known_passwords_array.contains(password)
     }
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -158,6 +153,15 @@ class CreateActivity : AppCompatActivity() {
 
         setSupportActionBar(findViewById(R.id.toolbar))
 
+        // Split word list in the background (this process can take a few seconds to complete)
+        GlobalScope.async {
+            val known_passwords_ = String(resources.openRawResource(
+                resources.getIdentifier("passwordlist", "raw", packageName)
+            ).readBytes())
+
+            known_passwords = known_passwords_.split("\n") as ArrayList<String>
+        }
+
         setContentView(R.layout.activity_create)
         back.setOnClickListener {
             Log.i("CREATE", "Back got clicked!")
@@ -186,6 +190,12 @@ class CreateActivity : AppCompatActivity() {
                         showError("Weak passphrase", "Passphrase has to be at least 8 characters long.")
                         return@OnClickListener
                     }
+                    if (passphrase != editTextLayout.passphrase2_input.text.toString()) {
+                        // Make a new alert, telling the user that his passphrase doesn't match the repeat field.
+                        dialogInterface.cancel()
+                        showError("Passphrase mismatch", "Both passphrases do not match.")
+                        return@OnClickListener
+                    }
 
                     // Check if password is found in our offline password list
                     if(passwordKnown(passphrase)) {
@@ -207,6 +217,16 @@ class CreateActivity : AppCompatActivity() {
 
 
         }
+        password_hide.setOnClickListener {
+            if (password_input.transformationMethod == HideReturnsTransformationMethod.getInstance()) {
+                password_input.transformationMethod = PasswordTransformationMethod.getInstance()
+                password_hide.setImageResource(R.drawable.ic_visibility_on)
+            } else {
+                password_input.transformationMethod = HideReturnsTransformationMethod.getInstance()
+                password_hide.setImageResource(R.drawable.ic_visibility_off)
+
+            }
+        }
 
         fa_input.isFocusable = false
 
@@ -242,6 +262,12 @@ class CreateActivity : AppCompatActivity() {
             if (result.contents.startsWith("otpauth://totp/")) {
                 fa_progress.visibility = View.VISIBLE
                 fa_uri = Uri.parse(result.contents)
+
+                if (fa_uri?.getQueryParameter("secret").toString() == "" || fa_uri?.getQueryParameter("secret") == null) {
+                    showError("Corrupt 2FA", "The scanned 2FA secret doesn't contain a secret!")
+                    return
+                }
+
                 val fa_generator = GoogleAuthenticator(base32secret = fa_uri?.getQueryParameter("secret").toString())
                 this.schema!!.custom.put("2fa", fa_uri?.getQueryParameter("secret").toString())
 
@@ -253,7 +279,12 @@ class CreateActivity : AppCompatActivity() {
                 // TODO: There is a bug. When the user changes his current app, this coroutine stops.
                 fa_coroutine = GlobalScope.launch(Dispatchers.Main) {
                     while (true) {
+                        try {
                             fa_input.setText(fa_generator.generate())
+                        } catch (error: IllegalArgumentException) {
+                            showError("Corrupt 2FA", "The scanned 2FA secret is corrupt and therefore no codes can be generated.")
+                            return@launch
+                        }
 
                         var seconds_remaining = CryptoOperations().getRemainingTOTPTime()
                         Log.i("2FA Generator", "Remaining: $seconds_remaining")
@@ -275,6 +306,8 @@ class CreateActivity : AppCompatActivity() {
                 }
 
                 fa_label.text = "${fa_uri?.path?.replace("/", "")} (${fa_uri?.getQueryParameter("issuer")})"
+            } else {
+                showError("No 2FA", "The scanned QR-Code has the wrong format.")
             }
         }
     }

app/src/main/java/com/github/mondei1/offpass/GeneratorActivity.kt

@@ -0,0 +1,11 @@
+package com.github.mondei1.offpass
+
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+
+class GeneratorActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_generator)
+    }
+}

app/src/main/java/com/github/mondei1/offpass/PassphraseActivity.kt

@@ -4,9 +4,12 @@ import android.content.Intent
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import android.text.Editable
+import android.view.View
 import kotlinx.android.synthetic.main.activity_passphrase.*
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.runBlocking
+import javax.crypto.BadPaddingException
+import kotlin.reflect.typeOf
 
 class PassphraseActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -22,9 +25,20 @@ class PassphraseActivity : AppCompatActivity() {
 
         decrypt_button.setOnClickListener {
             decrypt_button.text = "Decrypting ..."
+            var _continue = true;
+
             runBlocking {
+                try {
                     qrSchema.decrypt(raw, passphrase_input.text.toString())
+                } catch (err: BadPaddingException) {
+                    failed.visibility = View.VISIBLE
+                    decrypt_button.text = "Decrypt"
+                    _continue = false
+                    return@runBlocking
                 }
+            }
+
+            if(!_continue) return@setOnClickListener
 
             val intent: Intent = Intent(this, ViewActivity::class.java)
             intent.putExtra("decrypted_raw",qrSchema.decrypted_raw)

app/src/main/java/com/github/mondei1/offpass/ViewActivity.kt

@@ -8,21 +8,33 @@ import android.content.res.ColorStateList
 import android.graphics.Color
 import android.net.Uri
 import android.os.Bundle
+import android.text.method.HideReturnsTransformationMethod
+import android.text.method.PasswordTransformationMethod
 import android.util.Log
 import android.view.View
 import android.view.WindowManager
 import android.widget.TextView
 import androidx.appcompat.app.AppCompatActivity
 import dev.turingcomplete.kotlinonetimepassword.GoogleAuthenticator
+import kotlinx.android.synthetic.main.activity_create.*
 import kotlinx.android.synthetic.main.activity_view.*
-import kotlinx.coroutines.Dispatchers
+import kotlinx.android.synthetic.main.activity_view.back
-import kotlinx.coroutines.GlobalScope
+import kotlinx.android.synthetic.main.activity_view.email_input
-import kotlinx.coroutines.delay
+import kotlinx.android.synthetic.main.activity_view.fa_input
-import kotlinx.coroutines.launch
+import kotlinx.android.synthetic.main.activity_view.fa_label
+import kotlinx.android.synthetic.main.activity_view.fa_progress
+import kotlinx.android.synthetic.main.activity_view.password_hide
+import kotlinx.android.synthetic.main.activity_view.password_input
+import kotlinx.android.synthetic.main.activity_view.title_label
+import kotlinx.android.synthetic.main.activity_view.url_input
+import kotlinx.android.synthetic.main.activity_view.username_input
+import kotlinx.coroutines.*
 
 
 class ViewActivity : AppCompatActivity() {
 
+    var fa_coroutine: Job? = null
+
     override fun onBackPressed() {
         val i = Intent(this, MainActivity::class.java)
         i.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP
@@ -46,13 +58,25 @@ class ViewActivity : AppCompatActivity() {
             i.flags = Intent.FLAG_ACTIVITY_CLEAR_TOP
             startActivity(i)
         }
+        password_hide.setOnClickListener {
+            if (password_input.transformationMethod == HideReturnsTransformationMethod.getInstance()) {
+                password_input.transformationMethod = PasswordTransformationMethod.getInstance()
+                password_input.text = "123456"
+                password_hide.setImageResource(R.drawable.ic_visibility_on)
+            } else {
+                password_input.transformationMethod = HideReturnsTransformationMethod.getInstance()
+                password_input.text = qrSchema.password
+                password_hide.setImageResource(R.drawable.ic_visibility_off)
+
+            }
+        }
 
         qrSchema.decrypted_raw = intent.getStringExtra("decrypted_raw")!!
         qrSchema.parse(this)
 
         title_label.text = qrSchema.title
         username_input.setText(qrSchema.username, TextView.BufferType.EDITABLE)
-        password_input.setText(qrSchema.password, TextView.BufferType.EDITABLE)
+        password_input.setText("123456", TextView.BufferType.EDITABLE)
         email_input.setText(qrSchema.email, TextView.BufferType.EDITABLE)
         url_input.setText(qrSchema.website_url, TextView.BufferType.EDITABLE)
 
@@ -62,7 +86,7 @@ class ViewActivity : AppCompatActivity() {
             fa_label.text = "${fa_uri.path?.replace("/", "")} (${fa_uri.getQueryParameter("issuer")})"
             fa_progress.visibility = View.VISIBLE
 
-            GlobalScope.launch(Dispatchers.Main) {
+            fa_coroutine = GlobalScope.launch(Dispatchers.Main) {
                 while (true) {
                     fa_input.setText(fa_generator.generate())
 
@@ -88,4 +112,9 @@ class ViewActivity : AppCompatActivity() {
             fa_layout.visibility = View.GONE
         }
     }
+
+    override fun onStop() {
+        super.onStop()
+        fa_coroutine?.cancel(CancellationException("Activity is stopping"))
+    }
 }

app/src/main/res/drawable/baseline_arrow_forward_24.xml

@@ -1,10 +0,0 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="24dp"
-    android:height="24dp"
-    android:viewportWidth="24"
-    android:viewportHeight="24"
-    android:tint="?attr/colorControlNormal">
-  <path
-      android:fillColor="@android:color/white"
-      android:pathData="M12,4l-1.41,1.41L16.17,11H4v2h12.17l-5.58,5.59L12,20l8,-8z"/>
-</vector>

app/src/main/res/drawable/baseline_shuffle_24.xml

@@ -1,10 +0,0 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="24dp"
-    android:height="24dp"
-    android:viewportWidth="24"
-    android:viewportHeight="24"
-    android:tint="?attr/colorControlNormal">
-  <path
-      android:fillColor="@android:color/white"
-      android:pathData="M10.59,9.17L5.41,4 4,5.41l5.17,5.17 1.42,-1.41zM14.5,4l2.04,2.04L4,18.59 5.41,20 17.96,7.46 20,9.5L20,4h-5.5zM14.83,13.41l-1.41,1.41 3.13,3.13L14.5,20L20,20v-5.5l-2.04,2.04 -3.13,-3.13z"/>
-</vector>

app/src/main/res/drawable/baseline_visibility_24.xml

@@ -1,10 +0,0 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="24dp"
-    android:height="24dp"
-    android:viewportWidth="24"
-    android:viewportHeight="24"
-    android:tint="@color/colorPrimaryDark">
-  <path
-      android:fillColor="@android:color/white"
-      android:pathData="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5c-1.73,-4.39 -6,-7.5 -11,-7.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
-</vector>

app/src/main/res/layout/activity_create.xml

@@ -131,13 +131,13 @@
 
             <EditText
                 android:id="@+id/password_input"
-                android:layout_width="288dp"
+                android:layout_width="263dp"
-                android:layout_height="68dp"
+                android:layout_height="67dp"
                 android:layout_marginStart="16dp"
                 android:background="@color/colorPrimary"
                 android:ems="10"
                 android:fontFamily="sans-serif-black"
-                android:hint="You shouldn't see that"
+                android:hint="Secure password"
                 android:inputType="textPassword"
                 android:singleLine="true"
                 android:textSize="28sp"
@@ -235,19 +235,21 @@
                 app:layout_constraintStart_toEndOf="@+id/password_input"
                 app:layout_constraintTop_toTopOf="@+id/password_input"
                 app:layout_constraintVertical_bias="0.48000002"
-                app:srcCompat="@drawable/baseline_visibility_black_36" />
+                app:srcCompat="@drawable/ic_visibility_on" />
 
             <ImageButton
                 android:id="@+id/password_random"
-                android:layout_width="31dp"
+                android:layout_width="wrap_content"
-                android:layout_height="38dp"
+                android:layout_height="wrap_content"
                 android:layout_marginStart="8dp"
+                android:layout_marginEnd="15dp"
                 android:background="@color/colorPrimary"
                 android:tint="#000000"
                 app:layout_constraintBottom_toBottomOf="@+id/password_input"
+                app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintStart_toEndOf="@+id/password_hide"
                 app:layout_constraintTop_toTopOf="@+id/password_input"
-                app:srcCompat="@drawable/baseline_sd_storage_24" />
+                app:srcCompat="@drawable/ic_autorenew" />
         </androidx.constraintlayout.widget.ConstraintLayout>
     </ScrollView>
 

app/src/main/res/layout/activity_generator.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".GeneratorActivity">
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_passphrase.xml

@@ -9,8 +9,8 @@
 
     <EditText
         android:id="@+id/passphrase_input"
-        android:layout_width="234dp"
+        android:layout_width="286dp"
-        android:layout_height="wrap_content"
+        android:layout_height="61dp"
         android:layout_marginStart="88dp"
         android:layout_marginEnd="89dp"
         android:backgroundTint="#757575"
@@ -27,8 +27,7 @@
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
-        app:layout_constraintVertical_bias="0.513" />
 
     <Button
         android:id="@+id/decrypt_button"
@@ -36,7 +35,7 @@
         android:layout_width="152dp"
         android:layout_height="59dp"
         android:layout_marginStart="161dp"
-        android:layout_marginTop="72dp"
+        android:layout_marginTop="48dp"
         android:layout_marginEnd="162dp"
         android:background="#00FFFFFF"
         android:backgroundTint="#001C1C1C"
@@ -45,6 +44,7 @@
         android:textColor="@color/colorPrimary"
         android:textSize="18sp"
         app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.484"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/passphrase_input" />
 
@@ -62,4 +62,20 @@
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent" />
+
+    <TextView
+        android:id="@+id/failed"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="180dp"
+        android:layout_marginEnd="180dp"
+        android:layout_marginBottom="40dp"
+        android:fontFamily="sans-serif-black"
+        android:text="Wrong Passphrase"
+        android:textColor="#E53935"
+        android:textSize="18sp"
+        android:visibility="invisible"
+        app:layout_constraintBottom_toTopOf="@+id/passphrase_input"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent" />
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_view.xml

@@ -100,11 +100,12 @@
                 android:layout_height="68dp"
                 android:layout_marginStart="16dp"
                 android:background="@color/colorPrimary"
-                android:ems="10"
                 android:fontFamily="sans-serif-black"
+                android:gravity="center_vertical"
                 android:inputType="textPassword"
                 android:singleLine="true"
-                android:textSize="28sp"
+                android:textColor="@color/colorPrimaryDark"
+                android:textSize="42sp"
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toBottomOf="@+id/password_label" />
 
@@ -162,13 +163,13 @@
                 android:id="@+id/password_hide"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:layout_marginStart="60dp"
+                android:layout_marginStart="28dp"
                 android:background="@color/colorPrimary"
                 app:layout_constraintBottom_toBottomOf="@+id/password_input"
                 app:layout_constraintStart_toEndOf="@+id/password_input"
                 app:layout_constraintTop_toTopOf="@+id/password_input"
-                app:layout_constraintVertical_bias="0.437"
+                app:layout_constraintVertical_bias="0.45"
-                app:srcCompat="@drawable/baseline_visibility_black_36" />
+                app:srcCompat="@drawable/ic_visibility_on" />
 
         </androidx.constraintlayout.widget.ConstraintLayout>
     </ScrollView>

app/src/main/res/layout/create_bar.xml

@@ -1,64 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.appcompat.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
-    android:layout_width="match_parent"
-    android:layout_height="wrap_content"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:background="@color/colorPrimaryDark"
-    app:title="Create">
-
-    <androidx.constraintlayout.widget.ConstraintLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content">
-
-        <Button
-            android:id="@+id/back"
-            style="@style/Widget.AppCompat.Button.Borderless"
-            android:layout_width="47dp"
-            android:layout_height="50dp"
-            android:layout_marginEnd="6dp"
-            android:drawableTop="@drawable/baseline_arrow_forward_white_36"
-            android:text=""
-            app:layout_constraintEnd_toEndOf="parent"
-            app:layout_constraintTop_toTopOf="parent" />
-
-        <Button
-            android:id="@+id/settings"
-            style="@style/Widget.AppCompat.Button.Borderless"
-            android:layout_width="56dp"
-            android:layout_height="50dp"
-            android:layout_marginEnd="52dp"
-            android:drawableTop="@drawable/baseline_settings_white_36"
-            android:scaleX="1"
-            android:scaleY="1"
-            android:text=""
-            app:layout_constraintEnd_toEndOf="parent"
-            app:layout_constraintTop_toTopOf="parent" />
-
-        <Button
-            android:id="@+id/settings2"
-            style="@style/Widget.AppCompat.Button.Borderless"
-            android:layout_width="56dp"
-            android:layout_height="50dp"
-            android:layout_marginEnd="108dp"
-            android:drawableTop="@drawable/baseline_sd_storage_24"
-            android:scaleX="1"
-            android:scaleY="1"
-            android:text=""
-            android:textColor="#000000"
-            app:layout_constraintEnd_toEndOf="parent"
-            app:layout_constraintTop_toTopOf="parent" />
-
-        <TextView
-            android:id="@+id/print_button"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="8dp"
-            android:text="Create"
-            android:textColor="@color/colorPrimary"
-            android:textSize="24sp"
-            app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toTopOf="parent" />
-
-    </androidx.constraintlayout.widget.ConstraintLayout>
-
-</androidx.appcompat.widget.Toolbar>

app/src/main/res/layout/dialogpassphrase.xml

@@ -11,11 +11,22 @@
         android:id="@+id/passphrase_input"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
+        android:inputType="textPassword"
         android:backgroundTint="@color/colorPrimary"
         android:textColorHint="@color/colorPrimary"
         android:textColor="@color/colorPrimary"
         android:hint="Enter passphrase"/>
 
+    <EditText
+        android:id="@+id/passphrase2_input"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:inputType="textPassword"
+        android:backgroundTint="@color/colorPrimary"
+        android:textColorHint="@color/colorPrimary"
+        android:textColor="@color/colorPrimary"
+        android:hint="Repeat passphrase"/>
+
     <EditText
         android:id="@+id/hint_input"
         android:layout_width="match_parent"

app/src/main/res/values-round/strings.xml

@@ -1,3 +1 @@
-<resources>
+<resources></resources>
-    <string name="hello_world">Hello Round World!</string>
-</resources>

app/src/main/res/values/dimens.xml

@@ -4,12 +4,10 @@
     Because the window insets on round devices are larger than 15dp, this padding only applies
     to square screens.
     -->
-    <dimen name="box_inset_layout_padding">0dp</dimen>
 
     <!--
     This padding applies to both square and round screens. The total padding between the buttons
     and the window insets is box_inset_layout_padding (above variable) on square screens and
     inner_frame_layout_padding (below variable) on round screens.
     -->
-    <dimen name="inner_frame_layout_padding">5dp</dimen>
 </resources>

app/src/main/res/values/strings.xml

@@ -1,7 +1,5 @@
 <resources>
     <string name="app_name">OffPass</string>
-    <string name="qr_schema_support">1</string>
-    <string name="title_activity_create">CreateActivity</string>
     <!--
     This string is used for square devices and overridden by hello_world in
     values-round/strings.xml for round devices.