diff --git a/module/mifare.cpp b/module/mifare.cpp
index a6960ee..de253ed 100644
--- a/module/mifare.cpp
+++ b/module/mifare.cpp
@@ -1049,3 +1049,19 @@ void Mifare::data_setKey(int sector, KeyType keyType, const QString &key)
     else
         keyBList->replace(sector, key);
 }
+
+void Mifare::data_fillKeys()
+{
+    for(int i = 0; i < cardType.sectors; i++)
+    {
+        if(!data_isKeyValid(keyAList->at(i)))
+        {
+            keyAList->replace(i, "FFFFFFFFFFFF");
+        }
+        if(!data_isKeyValid(keyBList->at(i)))
+        {
+            keyBList->replace(i, "FFFFFFFFFFFF");
+        }
+    }
+    data_syncWithKeyWidget();
+}
diff --git a/module/mifare.h b/module/mifare.h
index c496b1e..ddc4011 100644
--- a/module/mifare.h
+++ b/module/mifare.h
@@ -118,6 +118,7 @@ public:
     void simulate();
     void loadSniff(const QString& file);
     void saveSniff(const QString& file);
+    void data_fillKeys();
 public slots:
 signals:
 
diff --git a/ui/mainwindow.cpp b/ui/mainwindow.cpp
index b93ff86..4464ca8 100644
--- a/ui/mainwindow.cpp
+++ b/ui/mainwindow.cpp
@@ -223,16 +223,21 @@ void MainWindow::on_MF_checkAllBox_stateChanged(int arg1)
     ui->MF_checkAllBox->blockSignals(false);
 }
 
-void MainWindow::on_MF_data2KeyBotton_clicked()
+void MainWindow::on_MF_data2KeyButton_clicked()
 {
     mifare->data_data2Key();
 }
 
-void MainWindow::on_MF_key2DataBotton_clicked()
+void MainWindow::on_MF_key2DataButton_clicked()
 {
     mifare->data_key2Data();
 }
 
+void MainWindow::on_MF_fillKeysButton_clicked()
+{
+    mifare->data_fillKeys();
+}
+
 void MainWindow::on_MF_fontButton_clicked()
 {
     bool isOK = false;
diff --git a/ui/mainwindow.h b/ui/mainwindow.h
index 0fb94b3..37d89b1 100644
--- a/ui/mainwindow.h
+++ b/ui/mainwindow.h
@@ -103,9 +103,9 @@ private slots:
 
     void on_MF_File_saveButton_clicked();
 
-    void on_MF_data2KeyBotton_clicked();
+    void on_MF_data2KeyButton_clicked();
 
-    void on_MF_key2DataBotton_clicked();
+    void on_MF_key2DataButton_clicked();
 
     void on_MF_dataWidget_itemChanged(QTableWidgetItem *item);
 
@@ -139,6 +139,8 @@ private slots:
 
     void on_MF_checkAllBox_stateChanged(int arg1);
 
+    void on_MF_fillKeysButton_clicked();
+
 private:
     Ui::MainWindow* ui;
     QButtonGroup* typeBtnGroup;
diff --git a/ui/mainwindow.ui b/ui/mainwindow.ui
index 5603ed5..d678bdb 100644
--- a/ui/mainwindow.ui
+++ b/ui/mainwindow.ui
@@ -193,23 +193,30 @@
              </widget>
             </item>
             <item>
-             <widget class="QPushButton" name="MF_data2KeyBotton">
+             <widget class="QPushButton" name="MF_data2KeyButton">
               <property name="text">
-               <string>&gt;&gt;</string>
+               <string>KeyBlocks-&gt;Key</string>
               </property>
              </widget>
             </item>
             <item>
-             <widget class="QPushButton" name="MF_key2DataBotton">
+             <widget class="QPushButton" name="MF_key2DataButton">
               <property name="text">
-               <string>&lt;&lt;</string>
+               <string>KeyBlocks&lt;-Key</string>
+              </property>
+             </widget>
+            </item>
+            <item>
+             <widget class="QPushButton" name="MF_fillKeysButton">
+              <property name="text">
+               <string>Fill Keys</string>
               </property>
              </widget>
             </item>
             <item>
              <widget class="QPushButton" name="MF_fontButton">
               <property name="text">
-               <string>Fonts</string>
+               <string>Set Fonts</string>
               </property>
              </widget>
             </item>