def add_auth (self, user=None, password=None, pattern=None):
        """Add given authentication data."""
        if not user or not pattern:
            log.warn(LOG_CHECK,
            _("missing user or URL pattern in authentication data."))
            return
        entry = dict(
            user=user,
            password=password,
            pattern=re.compile(pattern),
        )
        self["authentication"].append(entry)
Add given authentication data.