diff --git a/main/gradebook/gradebook_display_certificate.php b/main/gradebook/gradebook_display_certificate.php
index 43b0d2a8e6..26a8060072 100644
--- a/main/gradebook/gradebook_display_certificate.php
+++ b/main/gradebook/gradebook_display_certificate.php
@@ -19,7 +19,6 @@ require_once 'lib/gradebook_functions.inc.php';
 require_once 'lib/be.inc.php';
 require_once 'lib/gradebook_data_generator.class.php';
 
-
 //extra javascript functions for in html head:
 $htmlHeadXtra[] =
 "<script>
@@ -35,113 +34,111 @@ api_block_anonymous_users();
 if (!api_is_allowed_to_edit()) {
 	api_not_allowed(true);
 }
+
+
+    
+$course_code = api_get_course_id();
+
 $interbreadcrumb[] = array ('url' => Security::remove_XSS($_SESSION['gradebook_dest']).'?',	'name' => get_lang('Gradebook'));
 $interbreadcrumb[] = array ('url' => '#','name' => get_lang('GradebookListOfStudentsCertificates'));
 $this_section = SECTION_COURSES;
 Display::display_header('');
 
 if ($_GET['action'] == 'delete') {
-    $certificate = new Certificate($_GET['certificate_id']);
-    $result = $certificate->delete();
-	if ($result ==true) {
-		Display::display_confirmation_message(get_lang('CertificateRemoved'));
-	} else  {
-		Display::display_error_message(get_lang('CertificateNotRemoved'));		
-	}
+    $check = Security::check_token('get');
+    if ($check) {
+        $certificate = new Certificate($_GET['certificate_id']);
+        $result = $certificate->delete();
+        Security::clear_token();
+        if ($result ==true) {
+            Display::display_confirmation_message(get_lang('CertificateRemoved'));
+        } else  {
+            Display::display_error_message(get_lang('CertificateNotRemoved'));		
+        }
+    }
 }
 
+$token = Security::get_token();
+
 echo Display::page_header(get_lang('GradebookListOfStudentsCertificates'));
-?>
+$cat_id = isset($_GET['cat_id']) ? (int)$_GET['cat_id'] : null;
 
-<table  class="data_table">
-	<?php
-	$cat_id = isset($_GET['cat_id']) ? (int)$_GET['cat_id'] : null;
+//@todo replace all this code with something like get_total_weight()
+$cats = Category :: load ($cat_id, null, null, null, null, null, false);
 
-	//@todo replace all this code with something like get_total_weight()
-    $cats = Category :: load ($cat_id, null, null, null, null, null, false);
-    
-    if (!empty($cats)) {
-        
-        //with this fix the teacher only can view 1 gradebook
-        if (api_is_platform_admin()) {
-            $stud_id= (api_is_allowed_to_edit() ? null : api_get_user_id());
-        } else {
-            $stud_id= api_get_user_id();
-        }
-        
-        $total_weight = $cats[0]->get_weight();
-        
-        $allcat  = $cats[0]->get_subcategories($stud_id, api_get_course_id(), api_get_session_id());
-        $alleval = $cats[0]->get_evaluations($stud_id);
-        $alllink = $cats[0]->get_links($stud_id);
-        
-        $datagen = new GradebookDataGenerator ($allcat,$alleval, $alllink);
-        
-        $total_resource_weight = 0;
-        if (!empty($datagen)) {    
-            $data_array = $datagen->get_data(GradebookDataGenerator :: GDG_SORT_NAME,0,null,true);
-            
-            if (!empty($data_array)) {
-                $newarray = array();
-                foreach ($data_array as $data) {
-                    $newarray[] = array_slice($data, 1);
-                }
-                
-                foreach($newarray as $item) {
-                    $total_resource_weight = $total_resource_weight + $item['2'];
-                }            
+if (!empty($cats)) {
+
+    //with this fix the teacher only can view 1 gradebook
+    if (api_is_platform_admin()) {
+        $stud_id= (api_is_allowed_to_edit() ? null : api_get_user_id());
+    } else {
+        $stud_id= api_get_user_id();
+    }
+
+    $total_weight = $cats[0]->get_weight();
+
+    $allcat  = $cats[0]->get_subcategories($stud_id, api_get_course_id(), api_get_session_id());
+    $alleval = $cats[0]->get_evaluations($stud_id);
+    $alllink = $cats[0]->get_links($stud_id);
+
+    $datagen = new GradebookDataGenerator ($allcat,$alleval, $alllink);
+
+    $total_resource_weight = 0;
+    if (!empty($datagen)) {    
+        $data_array = $datagen->get_data(GradebookDataGenerator :: GDG_SORT_NAME,0,null,true);
+
+        if (!empty($data_array)) {
+            $newarray = array();
+            foreach ($data_array as $data) {
+                $newarray[] = array_slice($data, 1);
             }
-        }    
-    
-        if ($total_resource_weight != $total_weight) {
-            Display::display_warning_message(get_lang('SumOfActivitiesWeightMustBeEqualToTotalWeight'));
+
+            foreach($newarray as $item) {
+                $total_resource_weight = $total_resource_weight + $item['2'];
+            }            
         }
+    }    
+
+    if ($total_resource_weight != $total_weight) {
+        Display::display_warning_message(get_lang('SumOfActivitiesWeightMustBeEqualToTotalWeight'));
     }
+}
+
+$certificate_list = get_list_users_certificates($cat_id);	
+
+if (count($certificate_list)==0) {
+    echo Display::display_warning_message(get_lang('NoResultsAvailable'));
+} else {
+    echo '<table class="data_table">';
     
-	$certificate_list = get_list_users_certificates($cat_id);	
-	
-	if (count($certificate_list)==0) {
-		echo Display::display_warning_message(get_lang('NoResultsAvailable'));
-	} else {
-		foreach ($certificate_list as $index=>$value) {
-	?>
-		<tr>
-		<td width="100%" class="actions">
-            <?php echo get_lang('Student').' : '.api_get_person_name($value['firstname'], $value['lastname']).' ( '.$value['username'].')' ?>
-		</td>		
-		</tr>
-	<tr>
-	<td>
-	<table class="data_table">
-		<?php
+    foreach ($certificate_list as $index=>$value) {
+        echo '<tr>
+                    <td width="100%" class="actions">'.get_lang('Student').' : '.api_get_person_name($value['firstname'], $value['lastname']).' ( '.$value['username'].')</td>';
+		echo '</tr>';
+        echo '<tr><td>
+            <table class="data_table">';
+		
 		$list_certificate = get_list_gradebook_certificates_by_user_id ($value['user_id'], $cat_id);		
 		foreach ($list_certificate as $value_certificate) {
-			?>
-			<tr >
-			<td width="50%"><?php echo get_lang('Score').' : '.$value_certificate['score_certificate'] ?></td>
-			<td width="30%"><?php echo get_lang('Date').' : '.api_convert_and_format_date($value_certificate['created_at']) ?></td>			
-			<td width="20%">
-			<?php			
-                //$url = "index.php?export_certificate=yes&cat_id=".$cat_id."&user=".$value['user_id'];
-                $url = api_get_path(WEB_PATH).'certificates/index.php?id='.$value_certificate['id'];
-    			$certificates = Display::url(get_lang('Certificate'), $url, array('target'=>'_blank', 'class' => 'btn'));
-    			echo $certificates;
-            ?>
-			 <a onclick="return confirmation();" href="gradebook_display_certificate.php?action=delete&cat_id=<?php echo $cat_id; ?>&certificate_id=<?php echo $value_certificate['id'] ?>">
-                <?php echo Display::return_icon('delete.png',get_lang('Delete')); ?>
-             </a>
-			 </td>
-			</tr>
-			<?php
-		}
-		?>
-		</table>
-	</td>
-	</tr>
-    <?php
+			echo '<tr>';
+			echo '<td width="50%">'.get_lang('Score').' : '.$value_certificate['score_certificate'].'</td>';
+			echo '<td width="30%">'.get_lang('Date').' : '.api_convert_and_format_date($value_certificate['created_at']).'</td>';
+			echo '<td width="20%">';
+			
+            //$url = "index.php?export_certificate=yes&cat_id=".$cat_id."&user=".$value['user_id'];
+            $url = api_get_path(WEB_PATH).'certificates/index.php?id='.$value_certificate['id'];
+            $certificates = Display::url(get_lang('Certificate'), $url, array('target'=>'_blank', 'class' => 'btn'));
+            
+            echo $certificates;
+            
+			echo '<a onclick="return confirmation();" href="gradebook_display_certificate.php?sec_token='.$token.'&cidReq='.$course_code.'&action=delete&cat_id='.$cat_id.'&certificate_id='.$value_certificate['id'].'">
+                    '.Display::return_icon('delete.png',get_lang('Delete')).'
+                  </a>';
+			echo '</td></tr>';			
 		}
-	}
-    ?>
-</table>
-<?php
+		echo '</table>';
+        echo '</td></tr>';    
+    }
+    echo '</table>';
+}
 Display::display_footer();
\ No newline at end of file