An Automatic Registration Product For Schools/Universities??

Has anything like this been done before?
Basically a product that you hold/carry/attach to your person.
And a static device (built into the doorframe perhaps, and/or entrances & exits)
Then all you have to do is walk into the lecture theatre/classroom and youre automatically registered. No effort would be needed to use the product other than to have it on you. It would do away with signatures/roll-calls etc.
The product could also act as an anti-truancy device sounding an alarm if a pupil leaves the school grounds unannounced.
And a safety device to deter kidnappers. Again sounding an alarm if a child is removed from school before the end of the school day.
Sorry if this is in the wrong forum, im trying to determine if something like this already exists.
Any advice/help much appreciated!