entityId

Hi,
I have a limitation of 120 characters for the entityId of my site but can't seem to find where to change it. By default the plugin takes the url of the site and adds "wp-content/plugins/saml-20-single-sign-on/saml/www/module.php/saml/sp/metadata.php/2"
Is there a way to change that ? To set ourself an id ?
Thanks for your help.