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Fighting Counterfeiters With Quantum Money
the_newsbeagle writes "This article discusses a proposal to create cash that can't be counterfeited by embedding quantum particles in banknotes. A counterfeiter trying to copy a real bill would have to precisely measure all the attributes of the embedded quantum particles — which is impossible under the tricky laws of quantum mechanics (PDF). MIT computer scientist Scott Aaronson, who famously offered a prize for anyone who could prove quantum computers are impossible, said, 'This is science fiction, but it’s science fiction that doesn’t violate any of the known laws of physics.'"
The day that we are able to control quantum decoherence and noise in currency that goes through a washing machine will be a great day. But I can assure you this is so far in the future economics will be a completely different creature, almost certainly not concerned with currency.
What happens when someone needs to look at the money to verify it's not counterfeit?
If a counterfeiter can't measure it to duplicate it...
...then how can the authorities measure it to verify it?
...checking to see if the note is a fake?
Where they have to use cats instead of the much simpler counterfeit checking pens.
This will be a profit loser and allergic shoppers will suffer in particular.
You never know if you still have any left until you open your wallet to check.
This Space Intentionally Left Blank
This article was written by an idiot. You can't measure all the properties of a quantum particle. But so what? You can't exploit it unless you have entangled particles. And it'll be a bit complicated to store your banknotes in total isolation from the environment.
Or you can just use bitcoin.
If you're tracking the serial numbers of a bill in a database, skip the quantum brainhurt and just do the same thing video game authors and cell phone companies do: make sure the serial number isn't being used in more than one place at a time. Duh.
Seriously, it's like trying to invent a phaser so you can light a campfire, when the rest of us would just use a match.
---
DRM is like antifreeze, to the MPAA/RIAA it's sweet, to the consumers it's poison.
I can't remember where I read about this, I believe it was Simon Singh's The Code Book but anyway this was first proposed as far back as 1970 by Stephen Wiesner. It's sort of odd that it reappears every now and then.
My work here is dung.
We could make all transactions digital and use quantum cryptography (which is being studied pretty closely already).
This is one of those things that might well work in a limited situation (tracking marked bills to reveal criminal activity, etc) but the cost of Encoding, recording, and (securely) logging every bill as it is printed just isnt something that would be feasible for the majority of bill denominations. Maybe if it was limited to large quantity bills or something...
Common Sense isn't as Common as people think...
As opposed to all those non-quantum electrons, protons, and neutrons embedded in there now, presumably....
From TFA:
So it's not as if this is some idea that people actually know how to implement....
Does this mean that you can either know how much cash you have, or where your wallet is, but not both?
I'll stick with gold, thanks.
I had a wallet stuffed with a quantum money all in a superposition. Unfortunately when I went to a car dealership to buy a Porche cash, the wavefunction of my cash collapsed into a dirt poor eigenstate and I was left destitute and penniless.
(FYI This is also how stock markets work)
And cant be anonymous. Besides if it can be created it can be copied. Its just a matter of making the cost of entry too high to be worthwhile.
---- Booth was a patriot ----
Looks like someone read one of Chaum's old blind signature scheme papers and some zero knowledge proof papers from the early 90s, then thought it would be cool to store the bits as quantum states instead of flash memory or bar codes (why?) and it got rammed thru a journalist filter to totally screw up the protocol.
If that is the case, its really important that unlike the journalists interpretation of the protocol, you have like 200 sigs and only break 100 to prove they're all probably real. That is, if 100 randomly selected sigs work then you know you've got 2**100 odds that its all legit (um, more or less) and you have no idea whats stored in the other 100 sigs but they're probably real sigs. But if you double spend, then enough SSSS shares will be unlocked (well, maybe all of them will be unlocked depending on scheme) to identify the double spender.
This cash idea in the above article would only work if each bill was spent precisely once before being returned to be reminted. Not unlike a gift card.
Oddly enough a complete digital cash protocol cannot be completely correctly described in one little /. post. But the TLDR version is something like:
1) A piece of cash doesn't get one sig it gets like 500
2) If you want 2**64 odds that its not fake, after you collect the 500, you make the other guy break your random choice of 64 of the sigs, leaving 500-64 good unbroken ones.
3) If you double spend a lot of mathematical tomfoolery (usually SSSS based) magically cracks enough sigs to figure out the double spenders name. This is actually the hard part.
Probably 10 years ago I did a 15 minute demo in a classroom of Chaum's digital cash system, with some major (huge) simplifications, using something like a whole box of thank you notes and envelopes (walmart to my rescue). I thought it was "old" at the time since it was more than half a decade old. I donno if there is anything newer/better or interesting results since then, haven't kept up. You still need a mint for every transaction, you just don't need a LIVE connection to the mint for every transaction, as I recall. I remember it was a PITA sealing and tearing up all my envelopes, and the prof liked my topic and liked my prop but it was a little slow paced for a good demo. And I remember I got a paper cut. Oh well.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Besides a slight cut in seigniorage, why don't they make American dollars more difficult to counterfeit? Using materials, colors, etc that would only allow the most skilled counterfeiters (ie, North Korea or other groups with state backing) to copy them?
A lot of foreign currency has different sizes of bills, little plastic windows, metallic inks (or it could be mylar) and so on that would be extremely challenging.
I know they've tried to make American money more difficult to counterfeit (micro-printing, watermarking, etc) but it seems like people just keep bleaching out the ink and turning $1s into $20s or $100s because its so darn easy, which in turn makes it easier for the pros to turn out really good fakes, especially overseas.
It's almost enough to make a guy put on his tin hat and try to think up reasons why the government would WANT the currency counterfeited, especially overseas where it would have less impact on the native dollar economy but keep the currency supply large enough to maintain dollar-as-defacto-currency status...
bill validators need to have this tech but outside of slots they will likely cost to much to put in.
what about remote areas??? some cash register systems may run the tapes overnight. But tieing up the phone for each transaction??
What about satellite internet that has lag, small bandwidth and rail fade.
A counterfeiter trying to copy a real bill would have to precisely measure all the attributes of the embedded quantum particles — which is impossible under the tricky laws of quantum mechanics (PDF).
OK, so how does this help to authenticate a genuine note?
Maybe I'll pay you Tuesday for a hamburger today.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Wow, and people said Bitcoin was impractical and ridiculous...
Finally money will be worth the paper it's printed on. Oh wait.
disclaimer: I am a you row pee'n
I think we just need to go back to latinum based currency
This is my signature. There are many like it, but this one is mine.
Practically, we do not have a problem with perfect counterfeits that simply cannot be spotted by an expert. In fact we already have an infallible system (serial numbers: we know all the bills in existence and if any duplicates turn up or numbers out of range we know that counterfeiting is going on and that those bills are counterfeit).
The problem with counterfeiting we actually have is that bills can relatively easily get past retailers and allow the owner to purchase stuff or launder it even if they would fail to pass scrutiny.
This, if you consider it a big problem, could be solved with current technology and current bills (all bills get scanned and the serial number verified).
Troll is not a replacement for I disagree.
Bank notes already have embedded quantum particles.
Is it even possible to store a photon? You can capture a photon. You can scatter a photon. I don't think you can store a photon.
And really, how do you keep the secret watermark a secret? Once the spec document for the watermark is written, someone will need to make the watermark verifying equipment. And once that equipment is made, it will be sold to someone who is not to be trusted.
My bank balance is both positive and negative until I observe it. I simply never observe it. The positive side usually wins.
APK quotes people (including myself) without context and should not be trusted. Just thought you should know.
When it costs eight or nine orders of magnitude more to produce the money than the face value of the money itself, that's generally regarded as a design flaw. It's a sure bet that you could absorb a whole heck of a lot of losses from counterfeiting for the cost of inventing new quantum particle manipulation and testing technologies and distributing them throughout a banking/finance system. By the time it pays for itself, you'd need to have currency that can survive commerce via warp drive.
Separate point -- even if the physics don't preclude the whole concept, what do you want to bet you couldn't do the testing in a non-destructive manner (i.e., without affecting the properties of the quantum particles). "Well, it WAS a real $20 bill. Oops."
The use of a portable XRF (Xray Fluorescence) scanner can quickly determine if money has been debased or not.
This article is about currency, which is a promise of money.
Radiation-tag them, like the time-tunnel did. As an aside, it could also discourage hoarding.
Clerk: That'll be $57.50
Me: This should cover it.
Clerk: Sir, this is a $1 bill.
Me: Well it was a $100 bill before you looked at it.
How about using gold for money? We already know that it can't be faked, and there are simple tests to see if it is real. Plus there that thing about thousands of years of a solid track record as money.
These theory guys would be totally helpless in the real world.
Bill collector: Did you send payment?
Debtor: Yes. Well, at least partial payment.
Bill collector: What do you mean partial?
Debtor: I am not sure. I can tell you when the money will arrive, but not how much it is, or I can tell you how much I paid, but not when it will get there. Your choice.
Bill collector: *facepalm*
Silence is a state of mime.
In normal economic times this is a profit center for the US Treasury. Long term rates are historically 4%. Instead of the treasury paying $40 for a 10-year bond, it pays nothing for the equivalent currency as long its is never returned to the Reserve Bank for one reason or another. That is the advantage of being the world's most popular cash currency. Something like $700B fr the $1000B in cash never returns to US banks.
The whole reason this is supposed to work is because, from the article:
"Thanks to the no-cloning theorem, a counterfeiter couldn’t measure all the attributes of each photon to produce a copy. Nor could he just measure the one attribute that mattered for each photon, because only the bank would know which attributes those were."
That is ridiculous on its face, because how is the bank going to keep that secret? How do people that aren't banks check the validity of a given note? If you want to prevent counterfeiting, you just have to make the notes prohibitively expensive to counterfeit. Once you kill the profit motive, you're set.
All Science Fiction doesn't violate the known laws of physics.
Being Scientifically Plausible is what separates Science Fiction from Fantasy.
Please don't be ignorant. This is Slashdot, if there's any bastion of facts about SciFi, we should be it (then again, this is TFS, I shouldn't expect too much).
If I can't measure it well enough to copy it, I can't measure it well enough to verify it, either. And if the verification is fuzzy, then I just need to copy it well enough to pass the verification. Which is always step 1 in the counterfeiting handbook.
I never know how much cash I have until I look in my wallet anyway...and when I do I can't figure how fast I spend it!
it only need to beat casual examination by untrained human eye, and *maybe* beat a few of the measure used by shop to check big bills (only if you counterfeit big bills). The rest of the measure are more for banks to catch the fake money so that it does not circulate forever, and to forbid small scale outfit (aka your photocopier or laser printer) to easily produce counterfeit money. But big outfit , aka organized criminal, will make bills good enough to fool your average folks.
C. Sagan : A demon haunted world:
http://www.amazon.com/gp/product/0345409469/
visit randi.org
... against the biggest counterfeiters: the world's central banks.
No Inflation Taxation without Representation
If it were possible to preserve coherence in currency it would require a central database to check so the question becomes what is the point/benefit of this exercise?
If the semantic is when you check the bill its value must be refreshed then what is the practical difference between quantum approach and simply storing a new validation code on transisters sewn into the note during the checking process?
Someone hands you a counterfit $100 bill and you fail to verify it. Your screwed with either the quantum or classic validation code either way because you don't know if it is valid or if the previous owner made a copy of the classic code.
Someone hands you a $100 bill and you verify it. You now know either the classic or quantum version is valid. In the classic version the validation code changes. Even if the previous owner knew the code it does not matter anymore cause its no longer valid.
It would be interesting to find a scenario where the quantum approach makes any difference over the classical approach in a full real world implementation.
Either way we loose to police states wet dream of being able to track, record and mine to the hilt all transactions. Aggregation of power corrupts. It's human nature.
The God of Israel say paper money is worthless! The only things valuable are copper, silver and gold, because YHWH ordered the ancient jews to amass exactly those captured treasures around his Ark and burn everything else of loot, after the bloodthirsty prophet Samuel had all of the seven surrounding "amelekite" nations utterly and completely exterminated in "haram" genocidal warfare.
Quantum dots do not turn worthless pieces of paper into valuable gold. Gold does not care about blood or urine sticking to it, it makes people blind with its shining, which is why it is valuable. One can make idols of it and people will get on all four to adore those. Most jewish names start with "Gold-" or contain "-gold-" and they are the most money-minded tribe on Earth.