feature 2727: improve password security with the use of PasswordHash class.

This class performs salt and multiple iterations. Already used in Wordpress,
Drupal, phpBB and many other web applications.

$conf['pass_convert'] is replaced by $conf['password_hash'] + $conf['password_verify']


git-svn-id: http://piwigo.org/svn/trunk@18889 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/functions_upgrade.php

@@ -247,12 +247,7 @@ WHERE '.$conf['user_fields']['username'].'=\''.$username.'\'
   }
   $row = pwg_db_fetch_assoc(pwg_query($query));
 
-  if (!isset($conf['pass_convert']))
-  {
-    $conf['pass_convert'] = create_function('$s', 'return md5($s);');
-  }
-
-  if ($row['password'] != $conf['pass_convert']($password))
+  if (!$conf['password_verify']($password, $row['password']))
   {
     array_push($page['errors'], l10n('Invalid password!'));
   }