User detection

I have couple of Drupal sites where I use Quiz and I think there is demand to be able to somehow detect the user. Is there any kind of clear and secure method to detect the user, I mean so that we could be able to verify that really him is doing (or did) the course / test and nobody was helping him? So classroom tests are still needed to be able to get some official certificates before we can really make sure that the user did the test by themselfs... I have heard that Coursera is using many methods to detect the users. One of the methods is to detect how the user is typing. Maybe they are tracking the rhythm of how the user is typing and if the rhythm changes the user is probably different etc. and the test is "failed"... Maybe they first ask user to write a sample , and while the course is going, user is asked to give another typing samples and then they compare them... Actually I don't know how it works, but that idea sounds quite good? Of course there are still many ways to cheat... Also verifying users manually so that they send picture and for example driving licence is one way but it does not tell much actually who is in the end doing the course or test. Could it be possible to verify user using front facing camera while doing the test? Maybe taking pictures time to time. I think even iPhone fingerprint reader is not enough, we need live camera feed which can be used later to verify that the user really was there or was there someone else doing the course for him. Okey, maybe this task sounds impossible..also browser should be locked somehow. Maybe there sould be a notice that if focus goes away from the course window, the test is automatically failed. So users cant check answers from Google... If someone could create a module (or some kind of service) which could detect and verify that the user is really him and nobody is helping him while doing the course, I think it would be good business. Or is there already these kind of services available for eLearning ?