diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index ad18d9ded5e..4816cb698b4 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -6849,12 +6849,17 @@ class emoticon_manager {
  *
  * @todo Finish documenting this function
  *
- * @param string $data Data to encrypt
- * @return string The now encrypted data
+ * @param string $data        Data to encrypt.
+ * @param bool $usesecurekey  Lets us know if we are using the old or new password.
+ * @return string             The now encrypted data.
  */
-function rc4encrypt($data) {
-    $password = get_site_identifier();
-    return endecrypt($password, $data, '');
+function rc4encrypt($data, $usesecurekey = false) {
+    if (!$usesecurekey) {
+        $passwordkey = 'nfgjeingjk';
+    } else {
+        $passwordkey = get_site_identifier();
+    }
+    return endecrypt($passwordkey, $data, '');
 }
 
 /**
@@ -6862,12 +6867,17 @@ function rc4encrypt($data) {
  *
  * @todo Finish documenting this function
  *
- * @param string $data Data to decrypt
- * @return string The now decrypted data
+ * @param string $data        Data to decrypt.
+ * @param bool $usesecurekey  Lets us know if we are using the old or new password.
+ * @return string             The now decrypted data.
  */
-function rc4decrypt($data) {
-    $password = get_site_identifier();
-    return endecrypt($password, $data, 'de');
+function rc4decrypt($data, $usesecurekey = false) {
+    if (!$usesecurekey) {
+        $passwordkey = 'nfgjeingjk';
+    } else {
+        $passwordkey = get_site_identifier();
+    }
+    return endecrypt($passwordkey, $data, 'de');
 }
 
 /**
diff --git a/lib/sessionlib.php b/lib/sessionlib.php
index 73cbf2a1fb6..35a94f7a98e 100644
--- a/lib/sessionlib.php
+++ b/lib/sessionlib.php
@@ -821,14 +821,14 @@ function set_moodle_cookie($username) {
         return;
     }
 
-    $cookiename = 'MOODLEID_'.$CFG->sessioncookie;
+    $cookiename = 'MOODLEID1_'.$CFG->sessioncookie;
 
     // delete old cookie
     setcookie($cookiename, '', time() - HOURSECS, $CFG->sessioncookiepath, $CFG->sessioncookiedomain, $CFG->cookiesecure, $CFG->cookiehttponly);
 
     if ($username !== '') {
         // set username cookie for 60 days
-        setcookie($cookiename, rc4encrypt($username), time()+(DAYSECS*60), $CFG->sessioncookiepath, $CFG->sessioncookiedomain, $CFG->cookiesecure, $CFG->cookiehttponly);
+        setcookie($cookiename, rc4encrypt($username, true), time()+(DAYSECS*60), $CFG->sessioncookiepath, $CFG->sessioncookiedomain, $CFG->cookiesecure, $CFG->cookiehttponly);
     }
 }
 
@@ -844,15 +844,15 @@ function get_moodle_cookie() {
         return '';
     }
 
-    $cookiename = 'MOODLEID_'.$CFG->sessioncookie;
+    $cookiename = 'MOODLEID1_'.$CFG->sessioncookie;
 
     if (empty($_COOKIE[$cookiename])) {
         return '';
     } else {
-        $username = rc4decrypt($_COOKIE[$cookiename]);
+        $username = rc4decrypt($_COOKIE[$cookiename], true);
         if ($username === 'guest' or $username === 'nobody') {
             // backwards compatibility - we do not set these cookies any more
-            return '';
+            $username = '';
         }
         return $username;
     }