Public: Currency: Coin
Mu Money   (+2, -2)  [vote for, against]
No more heavy coins in your pocket

Everybody says that credit cards and electronic money will be the future, but I think/hope that the anonymous money that we currently have in the form of paper and metal coins stays for a while still. But metal coins are heavy and paper also has its problems, so here is the idea.

Make all “cash” in the form of plastic coins from recycled PET bottles. Different denominations have different shapes so humans can easily tell them apart. Embedded in each coin is a Mu chip (link). It is an RFID chip that only can be read from very close up (1/8 inch at most) if one uses the on-chip antenna. That way nobody can read through your pocket how much money you have.

Different from current concepts that suggest such chips as a safety feature in this idea the chip IS the coin. The RFID chips don’t carry a serial number, but an ID that indicates the value of the coin. Higher value coins could also have a small sliver of platinum embedded. It serves as proof of ownership so you can get a replacement at a bank if the plastic burns up (must show your ID and do paperwork in that case).

Such coins would be cheaper to make in large quantity, but harder to fake in a backyard operation because it takes a major outfit to make the chips. Suspicious individuals could carry a key ring gadget that allows reading one coin at a time. At a store the customer would throw the coins on a reader tray and the cash register would automatically sort it out and give change. The mechanism to identify coins in vending machines would cost a tiny fraction of the mechanical systems in use today. People with metal allergies would not have crumbly skin any more, and best of all: no more sagging pockets filled with pennies.
-- kbecker, Jun 05 2004

(?) Mu chip
[kbecker, Oct 05 2004, last modified Oct 21 2004]

Reading distance http://www.rfidjour...rticleview/831/1/1/
[kbecker, Oct 05 2004, last modified Oct 21 2004]

Nipponia: µ-chip (two pages down) http://web-japan.or...ture/feature05.html
"When I spoke with Hitachi's PR department, I discovered that the company developed its mu-chip in order to propose a new way to detect counterfeit money." [jutta, Oct 05 2004, last modified Oct 21 2004]

Archived µ-chip page https://wayback.arc.../mu-chip/p0001.html
same as [kbecker]'s link, which is 404 now. use the thing at the top to navigate through time [notexactly, Jun 13 2015]

To reduce the chance of backstreet copying, it might be possible that the value code is a 'signature' which uses a private key to create, and a public key allows anyone to inspect the value.
Different denominations could also be different colours.
-- Ling, Jun 06 2004

I think you’ve slightly damaged the idea by adding all these complicated details, but you still get a plus.
-- ldischler, Jun 06 2004

Nice idea, although they would be less durable than metal coinage and more expensive to produce.
-- hippo, Jun 06 2004

[hippo] I don't expect them to be very durable. An average of two years of circulation should do. The plastic used for soda bottles is very tough.

The RFID chips in these quantities will be cheap, not as cheap as a penny (link), but way cheaper than a quarter. Casting them into plastic will be way cheaper than minting.

[Ling] A signature would help, but the main copy protection would be the difficulty of making the chip in secret. An evil government or really big corporation could probably pull it off, but the average mafia will have a hard time. It takes many millions $$$ to set up the equipment wether you make a thousand or billions of chips. The equipment is also difficult to hide because it takes lots of exotic supplies and trained service personnel.
-- kbecker, Jun 06 2004

Interestingly, according to their PR department, Hitachi was looking at counterfeit-proofing money when they developed the chip.

Problem: Temperature resistance of the chip. From the manufacturer's FAQ:
Q: How resistant is the µ-chip to heat?
A: The operational temperature of the inlet (µ-chip with external antenna) enclosed is between 0 and 40 degrees centigrade. It can be used/stored in an environment between -20 and 75 degrees centigrade with no condensation. Work is progress to improve heat-resistance of the inlet.

[Ling] You can't use public key algorithms in a passive system. When you read this chip, you get a number, and it's always the same number; if you can fake a chip that sends this number back, you've made money.

Recycling PET is laudable, but I find plastic coins much less pleasant to handle than the metal ones, and flat wallets easier to deal with than bulky containers of plastic coins or tabs.
-- jutta, Jun 06 2004

[jutta], of course. But if it was a coded serial number then someone handing over a handful of coins, all with the same serial number, would have his collar felt rather quickly.
-- Ling, Jun 07 2004

I think we do just fine with the current, not so heavy notes... but I like the recycling part of the idea so, bun.
-- Pericles, Jun 09 2004

I was thinking about clear plastic coins, for 2 reasons.

1: They could contain gold or siver foil imprinted with some coinish picture. This would be so thin as to crumple immediately or wear away if used as an external veneer. Protected by the plastic these foil bits should have staying power plus some intrinsic worth.

2: Touchup. Coins wear. Plastic coins probably wear more. But if all that is desired is that the plastic be clear, gentle surface heat should suffice to close scratches and make the interior foil clearly visible again.

3: Opaque foil could itself enclose the RFID wire, concealing it from view as it is in the shape of the All-Seeing Eye of Providence and so a little creepy.
-- bungston, Jan 26 2011

// It is an RFID chip that only can be read from very close up (1/8 inch at most) if one uses the on-chip antenna. That way nobody can read through your pocket how much money you have. //


NEVER use lack of signal strength as a security mechanism!

Years ago—probably before 2004—it was demonstrated that you could carry around a high-powered RFID reader in a briefcase and read people's RFID cards from several meters away. All you need is enough transmit power to power the RFID transponder at long range and a sensitive enough receiver to pick up its response at long range. Both of these things are easily achievable.

Over the past several years, high-end cars have been mysteriously broken into while sitting outside their owners' homes, with no damage and in only a few seconds. The perpetrators were observed holding a mysterious device in each case. Eventually it was apparent that they could only do this on cars that had proximity keys—where you leave your keys in your pocket or purse, and the car unlocks when you walk near it. A few months ago, it was revealed that the mysterious device is simply a radio signal amplifier. It amplifies the signals between the car and the keys that are sitting wherever the owner keeps them inside their house. This causes the car to think the keys are right next to it, so it unlocks.

There is now pressure on the car makers to switch from using signal strength to using time of flight (timing the speed-of-light delay between sending a signal to the key and receiving a response). ToF is the only safe way to do radio proximity for security. Due to the speed of light being so high, however, ToF is impractical for measuring distances smaller than a few centimeters, requiring picosecond or femtosecond timing accuracy. A few centimeters should be adequate for this, with careful design of coin acceptors.

The other thing is that the coins themselves must implement ToF proximity measurement to be able to prevent walk-by checking of how much money you're carrying. (You can't depend on the bad guy's equipment to do your security for you.) Perhaps it would be better to simply keep them in an RFID-blocking wallet. (That works for the car keys: people have reported that putting them in the fridge or in Altoids tins makes them secure.)
-- notexactly, Jun 13 2015

random, halfbakery