Removes encryption and decryption, adds some error handling

Removes encryption and decryption from SessionCookie.  The encryption
and decrption will be handled elsewhere and can be enabled or disabled
via the cookies.encrypt config setting.

This fixes flash messaging/SessionCookie decoding failure when
cookies.encrypt = true

Slim/Middleware/SessionCookie.php

@@ -40,15 +40,11 @@
  * and instead serializes/unserializes the $_SESSION global
  * variable to/from an HTTP cookie.
  *
- * If a secret key is provided with this middleware, the HTTP
- * cookie will be checked for integrity to ensure the client-side
- * cookie is not changed.
- *
  * You should NEVER store sensitive data in a client-side cookie
- * in any format, encrypted or not. If you need to store sensitive
- * user information in a session, you should rely on PHP's native
- * session implementation, or use other middleware to store
- * session data in a database or alternative server-side cache.
+ * in any format, encrypted (with cookies.encrypt) or not. If you 
+ * need to store sensitive user information in a session, you should 
+ * rely on PHP's native session implementation, or use other middleware 
+ * to store session data in a database or alternative server-side cache.
  *
  * Because this class stores serialized session data in an HTTP cookie,
  * you are inherently limited to 4 Kb. If you attempt to store
@@ -79,9 +75,6 @@ public function __construct($settings = array())
             'secure' => false,
             'httponly' => false,
             'name' => 'slim_session',
-            'secret' => 'CHANGE_ME',
-            'cipher' => MCRYPT_RIJNDAEL_256,
-            'cipher_mode' => MCRYPT_MODE_CBC
         );
         $this->settings = array_merge($defaults, $settings);
         if (is_string($this->settings['expires'])) {
@@ -127,14 +120,14 @@ protected function loadSession()
             session_start();
         }
 
-        $value = \Slim\Http\Util::decodeSecureCookie(
-            $this->app->request()->cookies($this->settings['name']),
-            $this->settings['secret'],
-            $this->settings['cipher'],
-            $this->settings['cipher_mode']
-        );
+        $value = $this->app->getCookie($this->settings['name']);
+
         if ($value) {
-            $_SESSION = unserialize($value);
+            try {
+                $_SESSION = unserialize($value);
+            } catch (\Exception $e) {
+                $this->app->getLog()->error('Error unserializing session cookie value! ' . $e->getMessage());
+            }
         } else {
             $_SESSION = array();
         }
@@ -145,17 +138,12 @@ protected function loadSession()
      */
     protected function saveSession()
     {
-        $value = \Slim\Http\Util::encodeSecureCookie(
-            serialize($_SESSION),
-            $this->settings['expires'],
-            $this->settings['secret'],
-            $this->settings['cipher'],
-            $this->settings['cipher_mode']
-        );
+        $value = serialize($_SESSION);
+
         if (strlen($value) > 4096) {
             $this->app->getLog()->error('WARNING! Slim\Middleware\SessionCookie data size is larger than 4KB. Content save failed.');
         } else {
-            $this->app->response()->setCookie(
+            $this->app->setCookie(
                 $this->settings['name'],
                 array(
                     'value' => $value,
@@ -174,31 +162,49 @@ protected function saveSession()
     * Session Handler
     *******************************************************************************/
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function open($savePath, $sessionName)
     {
         return true;
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function close()
     {
         return true;
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function read($id)
     {
         return '';
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function write($id, $data)
     {
         return true;
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function destroy($id)
     {
         return true;
     }
 
+    /**
+     * @codeCoverageIgnore
+     */
     public function gc($maxlifetime)
     {
         return true;