The present disclosure relates to a cryptographic method for enabling access by a user device to services provided by a server in a set of reference areas. The method comprises at the user device: obtaining a set of reference credentials of the server certifying data indicating the reference areas; obtaining a location credential certifying location data indicating the current location of the user device; generating an authentication token comprising a cryptographic proof for proving that the current location of the user device certified by the location credential matches at least one reference area certified by the set of reference credentials; sending the authentication token to the server for accessing the services by the user device in the at least one reference area.