diff --git a/killer-chat.php b/killer-chat.php
index e167404..b7bc18a 100644
--- a/killer-chat.php
+++ b/killer-chat.php
@@ -1,40 +1,22 @@
+<?php	
+	require './credentials.php';
+	require './php/utils.php';
+	require_once('./php/security.php');
+	
+	date_default_timezone_set("Europe/Madrid");
+
+	Security::checkIsSignedIn();
+?>
+
 <head>
 <link rel="stylesheet" type="text/css" href="//fonts.googleapis.com/css?family=Open+Sans" />
 <link rel="stylesheet" href="./css/basic.css" />
 <link rel="stylesheet" href="./css/main.css" />
 
-<?php	
-	require './credentials.php';
-	require './php/utils.php';
-	
-	$credentials = new Credentials();
-	$usersdb = $credentials->usersdb;
-	$mortsdb = $credentials->mortsdb;
-	
-	date_default_timezone_set("Europe/Madrid");
-	
-	$user = $_COOKIE['user']; // (int)$_POST['user'];
-	$password = $_COOKIE['password']; // isset($_POST['password']) ? md5($_POST['password']) : '';
-
-	if (!isset($_COOKIE['user']) or $_COOKIE['user'] == '') {
-		die("<script>window.location.href = './'</script>");
-	} else if (isset($_COOKIE['password'])) {
-		$query_password = "SELECT password FROM $usersdb WHERE id=$user";
-		if (query($query_password)->fetch_row()[0] != $password) {
-			// Unset variables
-			setcookie('user', '', -1, "/");
-			setcookie('password', '', -1, "/");
-			
-			die("<script>window.location.href = './?passwordchanged=1'</script>");
-		}
-	}
-?>
-
-
 <?php
-        $user = get_users($_COOKIE['user']);
-        $victim = get_users($user->quimata);
-        if ($user->mort) die("<script>window.location.href = './dead.php'</script>");
+	$user = get_users($_SESSION['id']);
+	$victim = get_users($user->quimata);
+	if ($user->mort) die("<script>window.location.href = './dead.php'</script>");
 ?>
 
 		<meta charset="UTF-8">
@@ -59,34 +41,25 @@
                         <div id="killer-messages">
                                 <div class="messages-sent">
                                         <?php
-                                                // Create connection
-                                                $credentials = new Credentials();
-                                                $conn = new mysqli($credentials->servername, $credentials->username, $credentials->password, $credentials->dbname);
-                                                if ($conn->connect_error) die("Connection failed: " . $conn->connect_error);
-                                                $conn->set_charset("utf8");
-                                               
-                                                $query_quielmata = "SELECT id FROM pastanaga WHERE quimata = " . $user->id;
+                                                $query_quielmata = "SELECT id FROM pastanaga WHERE quimata = " . (int)$user->id;
                                                 $quielmata = $conn->query($query_quielmata)->fetch_row()[0];
                                                 
                                                 // Execute query and save result
-                                                $query_msgs = "SELECT * FROM `missatges` WHERE (`sender_id` = ".$user->id." AND `receiver_id` = ".$quielmata .
-                                                        ") OR (`sender_id` = ".$quielmata." AND `receiver_id` = ".$user->id . ")";
+                                                $query_msgs = "SELECT * FROM `missatges` WHERE (`sender_id` = ".(int)$user->id." AND `receiver_id` = ".(int)$quielmata .
+                                                        ") OR (`sender_id` = ".(int)$quielmata." AND `receiver_id` = ".(int)$user->id . ")";
                                                 $result = $conn->query($query_msgs);
                                                 
                                                 while($res = $result->fetch_row()) {
                                                         if ($res[1] == $user->id) {
-                                                                echo "<div class='from-me'><div class='msg-content'>$res[4]</div><div class='meta-data'><span class='timestamp'>$res[3]</span><span class='seen'>".($res[5] == 0 ? 'Enviat' : 'Vist')."</span></div></div>";
+                                                                echo "<div class='from-me'><div class='msg-content'>".htmlspecialchars($res[4])."</div><div class='meta-data'><span class='timestamp'>$res[3]</span><span class='seen'>".($res[5] == 0 ? 'Enviat' : 'Vist')."</span></div></div>";
                                                         } else {
-                                                                echo "<div class='to-me'><div class='msg-content'>$res[4]</div><div class='meta-data'><span class='timestamp'>$res[3]</span><span class='seen'>".($res[5] == 0 ? 'Nou!' : '')."</span></div></div>";
+                                                                echo "<div class='to-me'><div class='msg-content'>".htmlspecialchars($res[4])."</div><div class='meta-data'><span class='timestamp'>$res[3]</span><span class='seen'>".($res[5] == 0 ? 'Nou!' : '')."</span></div></div>";
                                                         }
                                                 }
                           
                                                 // Update 'seen' messages
-                                                $query_seen = "UPDATE missatges SET `seen` = 1 WHERE `receiver_id` = " . $user->id . " AND `sender_id` != " . $user->quimata;
+                                                $query_seen = "UPDATE missatges SET `seen` = 1 WHERE `receiver_id` = " . (int)$user->id . " AND `sender_id` != " . (int)$user->quimata . " AND `seen` <> 1";
                                                 $conn->query($query_seen);
-                                                
-                                                // Close the connection 
-                                                $conn->close();
                                         ?>
                                 </div>
                                 <form action="./php/send_thread.php" method="POST">