diff --git a/controllers/before-begin/index.js b/controllers/before-begin/index.js
index a6a2159..6b870d0 100644
--- a/controllers/before-begin/index.js
+++ b/controllers/before-begin/index.js
@@ -1,4 +1,5 @@
 module.exports.index = function(req, res) {
+
     res.setHeader('Content-Type', 'text/html');
 
     res.render('index.jade', res.locals, function(err, result) {
diff --git a/controllers/intro/index.js b/controllers/intro/index.js
index a6a2159..18b37a2 100644
--- a/controllers/intro/index.js
+++ b/controllers/intro/index.js
@@ -1,4 +1,8 @@
 module.exports.index = function(req, res) {
+
+    req.session.workerId = req.params.workerId;
+    req.session.save();
+
     res.setHeader('Content-Type', 'text/html');
 
     res.render('index.jade', res.locals, function(err, result) {
diff --git a/controllers/intro/urls.js b/controllers/intro/urls.js
index 8bbe18c..873b090 100644
--- a/controllers/intro/urls.js
+++ b/controllers/intro/urls.js
@@ -1,3 +1,4 @@
 module.exports = {
     '/intro': 'index',
+    '/intro/:workerId': 'index',
 };
diff --git a/controllers/prototype/dbrequests.js b/controllers/prototype/dbrequests.js
index b7076dd..5fcf474 100644
--- a/controllers/prototype/dbrequests.js
+++ b/controllers/prototype/dbrequests.js
@@ -1,7 +1,7 @@
 // Polyfill of find array
 if (!Array.prototype.find) {
     Array.prototype.find = function(predicate) {
-        if (this == null) {
+        if (this === null || this === undefined) {
             throw new TypeError('Array.prototype.find a été appelé sur null ou undefined');
         }
         if (typeof predicate !== 'function') {
@@ -22,9 +22,42 @@ if (!Array.prototype.find) {
     };
 }
 
+// Production steps of ECMA-262, Edition 5, 15.4.4.21
+// Reference: http://es5.github.io/#x15.4.4.21
+if (!Array.prototype.reduce) {
+    Array.prototype.reduce = function(callback /*, initialValue*/) {
+        'use strict';
+        if (this === null || this === undefined) {
+            throw new TypeError('Array.prototype.reduce called on null or undefined');
+        }
+        if (typeof callback !== 'function') {
+            throw new TypeError(callback + ' is not a function');
+        }
+        var t = Object(this), len = t.length >>> 0, k = 0, value;
+        if (arguments.length == 2) {
+            value = arguments[1];
+        } else {
+            while (k < len && !(k in t)) {
+                k++;
+            }
+            if (k >= len) {
+                throw new TypeError('Reduce of empty array with no initial value');
+            }
+            value = t[k++];
+        }
+        for (; k < len; k++) {
+            if (k in t) {
+                value = callback(value, t[k], k, t);
+            }
+        }
+        return value;
+    };
+}
+
 var pg = require('pg');
 var pgc = require('../../private.js');
 var Log = require('../../lib/NodeLog.js');
+var async = require('async');
 
 /**
  *
@@ -605,7 +638,7 @@ function predicate(line) {
 
         return (
             (elt.recommendationStyle !== null && (elt.recommendationStyle.trim() === line.recommendationStyle.trim())) ||
-            line.id === elt.coinCombinationId
+            line.sceneId === elt.sceneId
         );
 
     };
@@ -1182,6 +1215,61 @@ DBReq.TutorialCreator.prototype.finish = function() {
     this.finishAction(this.finalResult.expId, this.finalResult.coins);
 };
 
+DBReq.UserVerifier = function(userId, finishAction) {
+    this.userId = userId;
+    this.finishAction = finishAction;
+    var self = this;
+
+    pg.connect(pgc.url, function(err, client, release) {
+        self.client = client;
+        self.release = release;
+
+        self.execute();
+    });
+};
+
+DBReq.UserVerifier.prototype.execute = function() {
+
+    var self = this;
+    this.client.query(
+        "SELECT id as \"expId\" FROM Experiment WHERE user_id = $1",
+        [self.userId],
+        function(err, result) {
+            if (result.rows.length !== 4) {
+                self.finish(false);
+            }
+
+            async.map(
+                result.rows,
+                function(elt, callback) {
+                    self.client.query(
+                        "SELECT count(*) > 5 AS ok FROM CoinClicked WHERE exp_id = $1",
+                        [elt.expId],
+                        function(err, result) {
+                            callback(null, result.rows[0].ok === true);
+                        }
+                    );
+                },
+                function(err, result) {
+                    var ok = result.reduce(function(prev, next) { return prev && next; });
+                    self.finish(ok);
+                }
+            );
+        }
+    );
+
+};
+
+DBReq.UserVerifier.prototype.finish = function(finalResult) {
+    this.release();
+
+    this.client = null;
+    this.release = null;
+    this.finishAction(finalResult);
+};
+
+
+
 /**
  * Try to get a user by id, and creates it if it doesn't exists
  * @param id {Number} id to test
@@ -1276,4 +1364,8 @@ DBReq.getLastExp = function(id, callback) {
     new DBReq.LastExpGetter(id, callback);
 };
 
+DBReq.verifyUser = function(id, callback) {
+    new DBReq.UserVerifier(id, callback);
+};
+
 module.exports = DBReq;
diff --git a/controllers/prototype/index.js b/controllers/prototype/index.js
index 3b325dd..582e179 100644
--- a/controllers/prototype/index.js
+++ b/controllers/prototype/index.js
@@ -82,7 +82,7 @@ module.exports.play = function(req, res) {
     db.getLastExp(req.session.userId, function(expId, sceneId, coinId, recoStyle, coins) {
 
         res.locals.scene = sceneToFunction(sceneId);
-        res.locals.recommendationStyle= recoStyle;
+        res.locals.recommendationStyle = recoStyle;
         res.locals.coins = coins;
 
         req.session.experiments.push({
@@ -236,7 +236,6 @@ module.exports.viewer = editorHelper('prototype_viewer.jade');
 module.exports.checker = editorHelper('prototype_checker.jade');
 
 module.exports.userstudy = function(req, res) {
-    res.setHeader('Content-Type', 'text/html');
 
     if (req.session.userId !== undefined) {
 
@@ -249,6 +248,9 @@ module.exports.userstudy = function(req, res) {
     req.session.identificationFailed = false;
     req.session.save();
 
+    res.locals.workerId = req.session.workerId;
+
+    res.setHeader('Content-Type', 'text/html');
     res.render('user_study.jade', res.locals, function(err, result) {
         res.send(result);
     });
diff --git a/controllers/prototype/views/user_study.jade b/controllers/prototype/views/user_study.jade
index 654dd5d..03a1c6b 100644
--- a/controllers/prototype/views/user_study.jade
+++ b/controllers/prototype/views/user_study.jade
@@ -39,7 +39,10 @@ block content
     form#form.form-signin(method="POST", action='/identification')
         h2 Please sign in
         label(for='inputId').sr-only Id
-        input#inputId.form-control(name="inputId", type="text", placeholder='Id', required, autofocus)
+        if (workerId === undefined)
+            input#inputId.form-control(name="inputId", type="text", placeholder='Id', required, autofocus)
+        else
+            input#inputId.form-control(name="inputId", type="text", placeholder='Id', required, autofocus, disabled, value="#{workerId}")
 
         .form-group
             label Gender
diff --git a/controllers/thankyou/index.js b/controllers/thankyou/index.js
index 4cb75df..d83310c 100644
--- a/controllers/thankyou/index.js
+++ b/controllers/thankyou/index.js
@@ -1,12 +1,28 @@
+var db = require('../prototype/dbrequests.js');
+var vcode = require('../../lib/vcode.js');
+
 module.exports.index = function(req, res) {
 
-    req.session = null;
-    res.locals.session = null;
+    db.verifyUser(req.session.userId, function(ok) {
 
-    res.setHeader('Content-Type', 'text/html');
+        if (ok) {
+
+            res.locals.vcode = vcode(req.session.workerId, req.session.campaignIp);
+
+        }
+
+        res.locals.workerId = req.session.workerId;
+        req.session = null;
+        res.locals.session = null;
+
+        res.setHeader('Content-Type', 'text/html');
+
+        res.render('index.jade', res.locals, function(err, result) {
+            console.log(err);
+            res.send(result);
+        });
 
-    res.render('index.jade', res.locals, function(err, result) {
-        res.send(result);
     });
+
 };
 
diff --git a/controllers/thankyou/views/index.jade b/controllers/thankyou/views/index.jade
index 821cda0..53a86d8 100644
--- a/controllers/thankyou/views/index.jade
+++ b/controllers/thankyou/views/index.jade
@@ -6,3 +6,8 @@ block content
         source(src="/static/data/music/thankyou.ogg")
         source(src="/static/data/music/thankyou.mp3")
 
+    if (vcode !== undefined)
+        p Your vcode is #{vcode}.
+    else if (workerId !== undefined)
+        p You have no vcode because you're bad
+
diff --git a/lib/vcode.js b/lib/vcode.js
index d920a74..be22910 100644
--- a/lib/vcode.js
+++ b/lib/vcode.js
@@ -1,7 +1,13 @@
 var hash = require('sha256');
 var secretKey = require('../private.js').microSecretKey;
 
-module.exports = function(campaignId, workerId) {
+module.exports = function(workerId, campaignId) {
+
+    if (campaignId === undefined) {
+
+        return 'mw-dummyvcode';
+
+    }
 
     return 'mw-' + hash(campaignId + workerId + secretKey);
 
diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
index 9f0914d..b1ba03c 100644
--- a/npm-shrinkwrap.json
+++ b/npm-shrinkwrap.json
@@ -2,6 +2,11 @@
   "name": "3d-interface",
   "version": "2.0.0",
   "dependencies": {
+    "async": {
+      "version": "1.4.2",
+      "from": "async@1.4.2",
+      "resolved": "https://registry.npmjs.org/async/-/async-1.4.2.tgz"
+    },
     "body-parser": {
       "version": "1.12.4",
       "from": "https://registry.npmjs.org/body-parser/-/body-parser-1.12.4.tgz",
diff --git a/package.json b/package.json
index c688c5e..abe4eb4 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,8 @@
         "serve-favicon": "2.3.0",
         "emailjs":"0.3.16",
         "three":"0.71.0",
-        "sha256":"0.2.0"
+        "sha256":"0.2.0",
+        "async":"1.4.2"
     },
     "repository" : {
         "type" : "git",
diff --git a/posts/identification/index.js b/posts/identification/index.js
index ff78dbc..436e7ca 100644
--- a/posts/identification/index.js
+++ b/posts/identification/index.js
@@ -9,7 +9,7 @@ module.exports.index = function(req, res) {
         if (!ok) {
 
             db.createUser(
-                req.body.inputId,
+                req.session.workerId || req.body.inputId,
                 req.body.inputAge,
                 req.body.inputGender === 'male',
                 req.body.input3dskills,