:O ! nice
I love to see that you are already into it.
Did you solve the counterfeiting? Because there was a problem. If you sell one then some other guy can make copies with the same information. If they are high price coins it is bound to happen.
My method to fix it, is to make an electronic wallet inside of the coin and a couple of LEDs, one to let you know if it is connected to the network, a button to run the algorithm , a LED to show error and another for success.
The algorithm is: have 2 wallets inside that coin and make they send signed messages in between each other (just an incremental number). You can then see one of the wallets and press the button, if there is a change then it is the real deal.
The system is not impossible, but it is quite hard to make in small scale.
Actually yes, I did solve the counterfeiting problem- to some extent as anything that can be 'made' can be 'counterfeited', that said though there are a couple unique factors involved: NFC chips have unique unchangeable ID's, so for one you can simply query the chip to see if its the real one. Secondly, future NFC chips will include special security tokens that will prevent them being cloned, as well as access counters that can tell you how many times the chip has been accessed. That makes the chips themselves pretty secure.
