rfid glass capsules with crypto channel implanted under your skin
Basically this kind of capsules provides a password of 196 byte.
is it good? let's check it out
It can uniquely identify a human around the world.
It's time stable, doesn't react with the immune system, and doesn't cause cancer.
It is chemically inert for humans, plants and animals
Doesn't need any battery, it's a true rfid low power system.
It is not based on the physical characteristics of a human being.
It can be easily applied with a pressure gun without anesthesia.
Cannot be spoofed and cannot be cloned (not easily).
You cannot forget it at home, it's always with you.
It is more secure than fingerprint, facial recognition.
It cannot be exploited to track your position.
It's a contact-less device but antennas need to be at mm of distance rather than meters.
But, where to implant?

And ...
... can it be damaged by XRAY or by computed axial tomography?
mumble

Implanting sounds easy, but for sure replacing such a device requires mini-surgery.
Nothing more serious than what a dentist does, anyway.
(
Ummmm, no, implanting such a rfid-capsule inside one in a dental capsule is probably not a good idea, even for how you would later authenticate, unless you like swallowing your smartphone and push it to the last molar tooth

)