diff --git a/build/api/core/AuthSystemDefault.php b/build/api/core/AuthSystemDefault.php
index e6b5814..17fb4dc 100644
--- a/build/api/core/AuthSystemDefault.php
+++ b/build/api/core/AuthSystemDefault.php
@@ -13,9 +13,68 @@
 
 	use \error\core\Err;
 	use \error\core\Error;
+	use \database\core\Repo;
+	use \database\repo\professor;
 
 	class AuthSystemDefault implements AuthSystem{
 
+
+		public function __construct(){
+
+			/* (1) Init session variables
+			---------------------------------------------------------*/
+			if( !isset($_SESSION['CAS'])  || !is_array($_SESSION['CAS'])  ) $_SESSION['CAS']  = [];
+			if( !isset($_SESSION['AUTH']) || !is_array($_SESSION['AUTH']) ) $_SESSION['AUTH'] = [];
+
+
+			/* (2) Check CAS
+			---------------------------------------------------------*/
+			if( isset($_SESSION['CAS']['login']) && isset($_SESSION['CAS']['ticket']) ){
+
+				/* (1) Get professor repo */
+				/** @var professor $prof_repo */
+				$prof_repo = Repo::getRepo('professor');
+
+				/* (2) Get professor with this login */
+				$by_login = $prof_repo->getByLogin($_SESSION['CAS']['login']);
+
+				/* (3) If found -> store useful information */
+				if( is_array($by_login) && isset($by_login['idProfesseur']) && isset($by_login['admin']) ){
+
+					$_SESSION['CAS']['admin'] = (bool) $by_login['admin'];
+					$_SESSION['CAS']['id']    = (int)  $by_login['idProfesseur'];
+
+				/* (4) If no login found -> remove CAS auth */
+				}else
+					$_SESSION['CAS'] = [];
+
+			}
+
+
+			/* (3) Process AUTH
+			---------------------------------------------------------*/
+			/* (1) cas_admin | cas_user */
+			if( isset($_SESSION['CAS']['admin']) && is_bool($_SESSION['CAS']['admin']) ){
+
+				// by default: cas_user
+				$_SESSION['AUTH'] = ['cas_user'];
+
+				// if admin: cas_admin
+				if( $_SESSION['CAS']['admin'] === true )
+					$_SESSION['AUTH'][] = ['cas_admin'];
+
+			}
+
+			/* (2) Other permissions */
+			// TODO
+		}
+
+
+
+
+
+
+
 		/* VERIFICATION DES ACCES EN FONCTION DE PERMISSIONS ATTENDUES
 		*
 		* @expected<array> 										Liste des permissions attendues
@@ -24,7 +83,51 @@
 		*
 		*/
 		public static function permission($expected){
-			return new Error(Err::Success);
+
+			/* (1) Check format -> if not array of array(s) -> ERROR
+			---------------------------------------------------------*/
+			/* (1) If not array -> ERROR */
+			if( !is_array($expected) )
+				return new Error(Err::FormatError);
+
+			/* (2) If not array of array(s) -> ERROR */
+			foreach($expected as $permission_group)
+				if( !is_array($permission_group) )
+					return new Error(Err::FormatError);
+
+
+			/* (2) For each OR group
+			---------------------------------------------------------*/
+			foreach($expected as $OR_group){
+
+				/* (1) By default suppose the group is valid */
+				// -> an empty group will grant permission to all
+				$valid_group = true;
+
+				/* (2) Check for each AND permission in the group */
+				foreach($OR_group as $AND_perm){
+
+					/* (3) If not in session.auth -> invalidate the permission group */
+					if( !in_array($AND_perm, $_SESSION['AUTH']) ){
+
+						$valid_group = false;
+						break;
+
+					}
+
+				}
+
+				/* (4) If valid group -> Success */
+				if( $valid_group )
+					return new Error(Err::Success);
+
+
+			}
+
+
+			/* (5) If no valid group -> permission error */
+			return new Error(Err::PermissionError);
+
 		}
 	}
 
diff --git a/build/api/module/casController.php b/build/api/module/casController.php
index 3561def..da64137 100644
--- a/build/api/module/casController.php
+++ b/build/api/module/casController.php
@@ -27,11 +27,11 @@ class casController{
 		// login:    https://sso.univ-pau.fr/cas/login?service=http://ptut.com:8080/api/v/1.0/cas
 		// validate: https://sso.univ-pau.fr/cas/serviceValidate?ticket=***TICKET***&service=http://ptut.com:8080/api/v/1.0/cas
 
-		/* (1) Check validity
+		/* (1) Check if already connected
 		---------------------------------------------------------*/
-		/* (1) Check origin */
-		// TODO
-
+		/* (1) If already -> return @cas_login */
+		if( in_array('cas_user', $_SESSION['AUTH']) )
+			return ['cas_login' => $_SESSION['CAS']['login']];
 
 		/* (2) Fail if no ticket */
 		if( !isset($_GET['ticket']) || !is_string($_GET['ticket']) || strlen($_GET['ticket']) < 1 )
@@ -68,6 +68,14 @@ class casController{
 			return ['error' => new Error(Err::PermissionError, 'cannot find cas login')];
 
 
+		/* (3) Store data in session
+		---------------------------------------------------------*/
+		$_SESSION['CAS'] = [
+			'login'  => $cas_login,
+			'ticket' => $ticket
+		];
+
+
 
 		return ['cas_login' => $cas_login ];