my $xpc = XML::LibXML::XPathContext->new($doc);
$xpc->registerNs('p', 'http://www.crtp.it');
$xpc->registerNs('p2', 'http://www.crpt.com');
my $finded = $xpc->findnodes("/p2:login/p:utenti[p:email='$email' and p:password='$digestpass']");