diff --git a/API.txt b/API.txt
index 895094b..73d5e9e 100644
--- a/API.txt
+++ b/API.txt
@@ -133,4 +133,28 @@ Arguments:
 (optional) bool $ignore_implementation Forces aes_make_iv to create and store a new IV even if the phpseclib implementation is used.
 
 Returns:
-nothing
\ No newline at end of file
+nothing
+
+---------------------------------------------------------------------------------
+Hook:
+void hook_aes_config_change($decrypt_params, $encrypt_params)
+
+Description:
+This hook provide ability for developers to reencrypt data when aes configuration changed.
+
+Arguments:
+$decrypt_params An associative array with decrypt arguments containing the following keys:
+ - base64encode bool Whether this encrypted string is base64 encoded or not.
+ - custom_key string Use this as the key rather than the stored one for this operation.
+ - custom_cipher string Use this cipher rather than the default one. (only with Mcrypt - ignored with phpseclib)
+ - custom_iv Use string this initialization vector instead of the default one.
+ - custom_implementation string Can be "phpseclib" or "mcrypt". Warning: Does not check if the requested implementation actually exists.
+
+$encrypt_params An associative array with encrypt arguments containing the following keys:
+ - bool $base64encode bool Whether to return the string base64 encoded (recommended for database insertion).
+ - $custom_key string Use this as the key rather than the stored one for this operation.
+ - $custom_cipher string Use this cipher rather than the default one. (only with Mcrypt - ignored with phpseclib)
+ - $custom_iv string Use this initialization vector instead of the default one.
+ - $custom_implementation string Can be "phpseclib" or "mcrypt". Warning: Does not check if the requested implementation actually exists.
+
+See: aes_aes_config_change();
diff --git a/aes.module b/aes.module
index 74ca64c..dca70ce 100644
--- a/aes.module
+++ b/aes.module
@@ -310,6 +310,7 @@ function aes_config_submit($form, &$form_state) {
     'custom_implementation' => NULL,
   );
   $do_reencypt = FALSE;
+
   // If the cipher has changed...
   if ($form_state['values']['aes_cipher'] != variable_get("aes_cipher", "rijndael-128")) {
     variable_set("aes_cipher", $form_state['values']['aes_cipher']);
@@ -356,6 +357,22 @@ function aes_config_submit($form, &$form_state) {
   }
 
   if ($do_reencypt) {
+    // Calling custom hook_aes_config_change from each module which implement this hook.
+    foreach (module_implements('aes_config_change') as $module) {
+       $function = $module . '_aes_config_change';
+      $function($decrypt_params, $encrypt_params);
+    }
+  }
+
+  variable_set("aes_viewing_method", $form_state['values']['view_method']);
+
+}
+
+/**
+ * Implements hook_aes_config_change().
+ */
+function aes_aes_config_change($decrypt_params, $encrypt_params) {
+    // Re encrypt user paswords.
     $accounts = db_select('aes_passwords', 'p')
       ->fields('p', array('uid', 'pass'))
       ->condition('uid', 0, '!=')
@@ -376,10 +393,6 @@ function aes_config_submit($form, &$form_state) {
     if (count($accounts)) {
       drupal_set_message(t("Updated the passwords of @updates_num users because of a change in encryption settings.", array('@updates_num' => count($accounts))));
     }
-  }
-
-  variable_set("aes_viewing_method", $form_state['values']['view_method']);
-
 }
 
 /**