1 function mk_hash(s) {

     2     return crypto.createHash('sha1').update(s).digest('hex')

     3 }

     4 

     5 function mk_cookie(c) {

     6     return c.toString() + "-" + mk_hash(c.toString())

     7 }

     8 

     9 function gt_cookie(s) {

    10     var splits = s.split("-", 2);

    11     var counter = parseInt(splits[0])

    12     if (mk_hash(counter.toString()) == splits[1]) {

    13         return counter

    14     } else { return 0 }

    15 }

    16 

    17 app.get('/', function(req, res){

    18     var counter = gt_cookie(req.cookies.counter) || 0;

    19     res.cookie('counter', mk_cookie(counter + 1));

    20     ...

    21 });

    22