diff --git a/src/Senhaunica.php b/src/Senhaunica.php
index ea6c006..06a2dba 100644
--- a/src/Senhaunica.php
+++ b/src/Senhaunica.php
@@ -12,40 +12,60 @@
  */
 class Senhaunica
 {
+    /**
+     * Namespace da SESSION
+     */
+    const NS = 'uspdev-senhaunica';
+
+    /**
+     * Método que verifica e executa o login
+     * 
+     * Processo do oauth: 
+     * primeiro processa step 1, que direciona o usuário para a página de login do Oauth;
+     * o retorno do oauth é direcionado para cá novamente que processa step 2;
+     * o step 2 redireciona para cá novamente que processa step 3 e 
+     * retorna os dados do usuário autenticado para a rota que chamou inicialmente
+     * 
+     * @param $clientCredentials
+     * @return Null|Array
+     */
     public static function login($clientCredentials = [])
     {
-        if (empty($clientCredentials)) {
-            $clientCredentials['identifier'] = getenv('SENHAUNICA_KEY');
-            $clientCredentials['secret'] = getenv('SENHAUNICA_SECRET');
-            $clientCredentials['callback_id'] = getenv('SENHAUNICA_CALLBACK_ID');
+        if (!session_id()) {
+            session_start();
         }
 
+        // se não passou as credentials por parâmetro vamos buscar no env
+        if (empty($clientCredentials)) {
+            $clientCredentials = [
+                'identifier' => getenv('SENHAUNICA_KEY'),
+                'secret' => getenv('SENHAUNICA_SECRET'),
+                'callback_id' => getenv('SENHAUNICA_CALLBACK_ID'),
+            ];
+        }
         $server = new ServerUSP($clientCredentials);
 
         // step 3: tudo ok
-        if (isset($_SESSION['token_credentials'])) {
-            $tokenCredentials = unserialize($_SESSION['token_credentials']);
-            $_SESSION['oauth_user'] = $server->getUserDetails($tokenCredentials);
-            session_write_close();
-            return $_SESSION['oauth_user'];
+        if (isset($_SESSION[self::NS]['token_credentials'])) {
+            $tokenCredentials = unserialize($_SESSION[self::NS]['token_credentials']);
+            $_SESSION[self::NS]['oauth_user'] = $server->getUserDetails($tokenCredentials);
+            return $_SESSION[self::NS]['oauth_user'];
         }
 
         // step 2: recebendo o retorno do oauth
         if (isset($_GET['oauth_token']) && isset($_GET['oauth_verifier'])) {
-            $temporaryCredentials = unserialize($_SESSION['temporary_credentials']);
+            $temporaryCredentials = unserialize($_SESSION[self::NS]['temporary_credentials']);
             $tokenCredentials = $server->getTokenCredentials($temporaryCredentials, $_GET['oauth_token'], $_GET['oauth_verifier']);
-            unset($_SESSION['temporary_credentials']);
-            $_SESSION['token_credentials'] = serialize($tokenCredentials);
-            $_SESSION['oauth_user'] = $server->getUserDetails($tokenCredentials);
-            session_write_close();
+            unset($_SESSION[self::NS]['temporary_credentials']);
+            $_SESSION[self::NS]['token_credentials'] = serialize($tokenCredentials);
+            $_SESSION[self::NS]['oauth_user'] = $server->getUserDetails($tokenCredentials);
             header('Location: ' . $_SERVER['PHP_SELF']);
             exit;
         }
 
         // step 1: credenciais temporárias e redirecionamento para login USP
         $temporaryCredentials = $server->getTemporaryCredentials();
-        $_SESSION['temporary_credentials'] = serialize($temporaryCredentials);
-        session_write_close();
+        $_SESSION[self::NS]['temporary_credentials'] = serialize($temporaryCredentials);
         $url = $server->getAuthorizationUrl($temporaryCredentials) . '&callback_id=' . $clientCredentials['callback_id'];
         header('Location: ' . $url);
         exit;
@@ -53,7 +73,7 @@ public static function login($clientCredentials = [])
 
     public static function getUserDetail()
     {
-        return isset($_SESSION['oauth_user']) ? $_SESSION['oauth_user'] : null;
+        return isset($_SESSION[self::NS]['oauth_user']) ? $_SESSION[self::NS]['oauth_user'] : null;
     }
 
     /**
@@ -63,14 +83,14 @@ public static function getUserDetail()
      */
     public static function obterVinculo($campo, $valores)
     {
-        if (!isset($_SESSION['oauth_user']['vinculo'])) {
+        if (!isset($_SESSION[self::NS]['oauth_user']['vinculo'])) {
             return null;
         }
         if (!is_array($valores)) {
             $valores = [$valores];
         }
         foreach ($valores as $valor) {
-            foreach ($_SESSION['oauth_user']['vinculo'] as $v) {
+            foreach ($_SESSION[self::NS]['oauth_user']['vinculo'] as $v) {
                 if ($v[$campo] == $valor) {
                     return $v;
                 }