We have implanted RFID inside inmate body for tracking purposes, ID the pooches, etc. My question is in near future where all newborns are required by law to be tagged using RFID is it possible to use them as weapon to terminate the target remotely via radiowave signal or perhaps through WiFi? Disregard ethical and moral issues how can we prevent unauthorized hacking of these implants? It would be better if such device can deliver non-lethal but high electricity to incapacitate the target on command if it is viable. Also how to design it to be extremely difficult and tedious to be removed illegally?
Short answer: No.
Longer answer: RFID tags are basically like a barcode that can be read with radio waves. They are an ID tag. That's literally the name: "radio frequency identification." RFID tags are already implanted in living things...particularly pets. The 'Microchip' that gets implanted in a pet, as a means of identification? Yeah...that is commonly an RFID tag. You can read information off of them, and (in some versions) write information to them. Something implanted in a person for identification purposes would be designed expressly to NOT be changeable, so that their ID couldn't be tampered with.
It's not like you have a computer in your arm or something, it's just an ID tag. And in the most likely case where the tags are read only, you can't even change the information stored on them because it is hardwired.
The way a modern RFID tag works is that when you hit it with a radio signal, it slightly modulates that signal in a way that represents the data stored on it. The reader detects these modulations, and interprets them. That's it.
Now, could you hit someone with enough energy to make the chip superheat and damage surrounding tissue? Sure! But that same amount of energy would probably harm the target directly, and that'd be a much more efficient use of resources.
EDIT: The only way this would work is if you had something else implanted. A bomb, an electrical weapon, whatever...and it was triggered by a specific transmission frequency to a logic circuit implanted in the skin that would trigger the device. But....you aren't weaponizing RFID...you are using RFID as a communication method, that could more efficiently be triggered by normal radio transmissions. Just to be clear, this system doesn't need to be anything advanced or large. It could be very simple...little more than a few transistors and a tiny battery
But, an RFID tag, by itself, cannot kill a person. It would need to be part of a system. And, in that case, there are more efficient ways of transmitting a kill-signal than RFID tags.
RFID tags are small. Often many get their power from the 'reading' equipment. So I see two small possibilities. One, it holds a one time dose of a chemical that can kill/disable host. The other is having it located very strategically so that a very small electric shock could trigger a crippling current. This would likely be in the neck somewhere near the spine. likely with a wire into the spinal column.
The 1992 film Fortress has a similar idea. All inmates in this ultra-high-tech private prison are forced to ingest a device called an "intestinator" that is equal parts tracking device, pain-compliance tool and anti-escape measure. Various minor offenses trigger pain, such as crossing a yellow "warning" line within the prison or ticking off prison staff. Serious offenses such as crossing a red line or attacking a guard trigger the device to detonate with fatal effects.
Chemical explosives typically have a maximum density, but you could think up a variation of your RFID capsule implanted in the brain stem. Even a small explosive charge triggered by an encrypted radio signal would damage the stem, cutting off impulses for unconscious muscle actions such as breathing and heartbeat.