Upvoted because while the reconstruction is not too convincing, it is hilarious that he's discovered the banks are cheating tourists by selling them under-weighted bank note sets & making up the difference with random pebbles & concrete parts.
You'd think they'd have no problem being honest about the count since they must shred a huge number of bills daily due to normal bill lifecycles, or that people would've shaken the containers and noticed, but apparently not!
There aren’t 138 bank notes in any of them. Even the ones that had no stones had only about 82 pieces (the ones with stones had about 20). I don’t think that’s a convincing explanation considering the inconsistency in terms of whether or not there are stones and the complete mismatch between the amount of notes advertised vs how much there actually is.
It would be pretty funny if there was some kind of scam going on here where the notes were actually being reconstructed and a small portion of each paperweight was siphoned off to support the crime (perhaps by diverting whole notes early in the shredding process). That could explain why some weights had fewer notes with rocks to make up the difference. Seems unlikely obviously in reality but there should probably be an investigation to figure out why the Hong Kong Monetary Authority visitor center is participating in fraudulent behavior.
In the 1990s, the Stasi Records Archive began reassembling documents that had been torn up by hand by the staff of the Ministry for State Security (MfS). This material had been stuffed into a total of 16,000 bags.1.7 million pages from 600 bags have been manually reconstructed, indexed and archived. Additionally, as part of a pilot project, a computer-assisted reconstruction program reassembled approximately 91,000 pages from 23 bags.
> The idea for this paper was discussed with the staff during my visit to the Hong Kong Monetary Authority visitor center. The paperweight souvenir is currently no longer available.
I was hoping the author managed to buy the last 100 of them and is selling them at HKD 5000 each to people who read this paper and want to try their luck.
Like the other commenter I’m amused that they included rocks in the shredded notes to make up weight.
I think something like this is unfortunately doomed to fail, as whilst there might ideally be approximately 138 banknotes worth of mass in there, it seems likely that the shreds are from thousands of different banknotes, and the container holds only a fraction of each whole note. Therefore no matter how good your reconstruction is, you simply won’t have the right pieces to work with.
While you might not be able to construct the entire banknote, there would probably be a high chance of many partial constructions. In and of itself interesting from a partially complete puzzle perspective. Plus, attempting to match varying serial numbers, dates, reference marks, while still having each bill vary.
Could probably be improved by doing 50-100 variations on each bill to give a general idea of the patterns possible within a zone. Such as: This area has 8 possible characters, with 36 possible entries /[a-zA-Z0-9]/. It has a fixed border with some constant pattern nearby. Show all the possible combos and then dice up the area a bunch of different ways.
On the partial constructions topic:
You have 350 of 1000 pieces of an image with some known general shape.
How much of the image can you reconstruct while still missing 2/3 of the pieces?
At the least has applications for image guessing. Also, agree on the false bank note contents, and how many people at the note shredding office are just stuffing their pockets with bank notes and then filling the cylinders with rocks? Great scam that probably almost nobody actually checks.
The practical value here isn't in banknotes, it's in shredded classified documents. That's the elephant in the room. And it's good for advancing pure research.
I compost all of my sensitive information that arrives by mail.
And whenever I need to dispose of something I can’t compost, like an old drivers license, I cut it into pieces and drip feed the pieces into the garbage over the course of a few months.
Call me paranoid but I think there will be a cottage industry in sifting through garbage once this tech gets mature enough!
Considering all of my confidential information has already been leaked by some tech entity or another, yeah a bit paranoid. Concentrated data is juicier than mining trash.
Putting it on paper in the first place is a big mistake because it probably isn't encrypted, it has probably been printed (printers are a bit scary in terms of security and privacy), there's cameras everywhere including in every pocket, and documents are easily duped, exfiltrated and observed, and you would likely have no easily-followed log of any of that. You also have to trust whoever does your disposal/recycling, and where there's people, there's dishonesty. Hence "zero trust" as a concept.
Interesting! What about it makes you sad? I'm happier than ever because I don't need to worry anymore about if something is safe, because I know it is safe.
Having sensitive data compromised would make me extremely sad.
Each banknote will have a unique serial number. So at least some part of the document will not be known in advance. Though serial numbers are well structured so you can take advantage of that.
>Among the most interesting papers are shredded secret documents pieced back together by the militants that detail attempts of the Central Intelligence Agency to recruit high-level Iranian officials, ayatollahs and exiles, foreign journalists and diplomats either as paid or ''unwitting'' agents in the months after the revolution in February 1979.
I’m surprised they could put them back together. When I shredded top secret documents in the navy when I was a kid, what came out into the bin outside was effectively powder. Those shredders could shred a broomstick! Literally, I shredded a broomstick once, it didn’t even slow down. They were tall so you had to climb on a ladder to reach the top, and they had a massive electric motor that spun a very heavy rotor very fast that would powder the documents. You threw multiple reams worth of paper at once.
It does seem a colossal failure that a potentially overrun location would not have the real industrial shredders and instead relies upon the consumer style.
It depends on what you deem as a failure. We are talking buying something for about $13 US and reassembling it to theoretically up to about $17,600 US.
Even if only, I don't know, 1/4 of the pieces are there, the potential to turn $13 into $4.5k isn't bad at all.
The limit of two souvenirs per visitor is interesting, perhaps they imagined someone would try this.
The trick, then, is to collude with other souvenir purchasers, similar to McDonald's Monopoly, so you can quickly swap your own duplicate pieces to others who need them. But unlike Mcdonald's Monopoly, there's probably no rare Park Place that virtually guarantees an instant win to whoever holds it.
The bank could do something like that. They could cut all the bills in two, and incinerate the left 60% of every single bill, so the souvenirs only contain shreds of the right 40%, thus guaranteeing that nobody can ever reconstruct 51% of a bill no matter how many souvenirs they have. But there seems to be no evidence that they're doing this.
I was just thinking about this at lunch today! I have been working through the Advent of Code 2020 problems. Day 20 involves a very simple version of the reassembly problem, putting together square tiles with fixed size overlapping border patterns. I did the first phase of the challenge "by hand," but I was wondering how fast it would be with the recent advances in CNNs and Transformer models.
Exactly what I though of when I saw the title. I had totally forgotten about this! I was fresh out of school in 2011 working my first full time job and took a shot at this challenge on my own in my spare time with a very naive approach using Python and OpenCV; I was way out of my depth but managed to get my name on the (very bottom of the) leaderboard :-)
In my country you can go to the bank and ask for the damaged banknotes to be replaced with new ones. As for the explanation how you come into possession of so much cash then I believe normal money laundering practices still apply
They gotta be recording the serial numbers and listing them as "cancelled" in some database somewhere, right? But with enough shredded pieces, you could always reconstruct a different number.
Nah. Counterfeiting never includes repairing, unless you find the most corrupt country to stretch the definition. In the USA, the Bureau of Engraving and Printing is who would sell the shredded currency (by the ounce) and their Mutilated Currency Division is who would redeem it (at face value). They are a federal agency so they'd pass the evidence to the FBI and charge you with conspiracy to defraud the United States.
Interestingly it seems to say you have to agree to all of that, and that if you break it your agreement to use shredded currency may be revoked, but it doesn't make any reference to laws or "we'll come arrest your ass" language.
That doesn't mean it's _not_ illegal, but it does tend to confirm my suspicion that nobody has thought to worry about it.
Nothing in the rules seem to indicate that you're not allowed to reassemble the shredded notes, or that you're not allowed to either use them as currency or request replacement for your "damaged" currency.
However, I am not a lawyer but I'd bet a court would rule that the act of shredding the currency was intended to permanently invalidate its use as currency, and any attempt to reverse that shredding via reassembly, combined with an attempt to pass off said reconstituted money as US currency, would constitute fraud. So while the rules don't seem to explicitly say you can't do it, it's implied that you can't.
Interesting that they specifically outlaw using it as packing material. I had several hundred thousand dollars of this stuff last year that I intended to use as packing material. I did wonder about the possibility of putting it back together.
Just so everyone is aware, you don’t have to buy shredded US currency. If you go to the museum inside your local (local?) Federal Reserve branch, they give you a bag of it for free.
I recommend going, if you’re ever in the vicinity of one. There will be all sorts of rare and obscure currency, plus odd things like stacks of $1,000,000 in various denominations for you to take photos with.
Replying to my own comment to add: You'd have to reassemble them by hand. Even if you find all the pieces, you have to arrange them properly, and then, what, tape them together? Who's going to accept that for spending?
The stained glass windows of the cathedral in Winchester, UK were smashed in the civil war. After the war they picked up the pieces and rebuilt the windows, but they no longer make a coherent picture. It would be amazing to use tech like this to reassemble them properly.
The lead borders follow smooth arcs, so the glass may have been ground down to fit the existing shaped holes, causing a lot to be lost.
The caption seems to suggest all of the windows were broken, but only one side of the church was reconstructed with all of the pieces. So that's 3/4ths lost there, possibly.
I could see computer vision finding the orientation of symbols and faces, and gathering similar patterns. I'm not sure how much farther it would get though.
They're not different codepoints, they're being rendered as mathematical markup by MathJax. This rendering includes using a LaTeX-esque font rather like Computer Modern.
Arxiv does this presumably because some papers have mathematical expressions in the titles and abstracts. For example https://arxiv.org/abs/2401.04991
I think the bank might get suspicious when the reassembled bank note looks like it was shredded and reconstituted. I guess you could say something like "My toddler thought it would be funny to shred a stack of money"
For a large amount it's likely that AML checks apply, but if you have most (> 50%) of a Bank of England note and can explain why they will give you new one instead.
The form says you need to provide ID if it's £700 or more, and they need witnessed ID for £10 000 or more for AML reasons, sadly you can't apply in person so no tearing up banknotes and popping into Threadneedle Street to do it on the spot as a tourist.
As that link mentions if the problem with your "damaged" note is that it was in a dye pack which exploded during your bank robbery, that's not an "accident" and you don't get an undyed replacement note - you're a crook, if you weren't smart enough to give a fake name and address you're getting arrested.
The shredded notes are bundled in large bales, then small bits are put in each souvenir. The odds of getting all of the pieces to even one banknote is small.
81 comments
[ 2.1 ms ] story [ 151 ms ] threadYou'd think they'd have no problem being honest about the count since they must shred a huge number of bills daily due to normal bill lifecycles, or that people would've shaken the containers and noticed, but apparently not!
It would be pretty funny if there was some kind of scam going on here where the notes were actually being reconstructed and a small portion of each paperweight was siphoned off to support the crime (perhaps by diverting whole notes early in the shredding process). That could explain why some weights had fewer notes with rocks to make up the difference. Seems unlikely obviously in reality but there should probably be an investigation to figure out why the Hong Kong Monetary Authority visitor center is participating in fraudulent behavior.
https://www.stasi-unterlagen-archiv.de/archiv/rekonstruktion...
Edit: link to the English version.
I was hoping the author managed to buy the last 100 of them and is selling them at HKD 5000 each to people who read this paper and want to try their luck.
I think something like this is unfortunately doomed to fail, as whilst there might ideally be approximately 138 banknotes worth of mass in there, it seems likely that the shreds are from thousands of different banknotes, and the container holds only a fraction of each whole note. Therefore no matter how good your reconstruction is, you simply won’t have the right pieces to work with.
Could probably be improved by doing 50-100 variations on each bill to give a general idea of the patterns possible within a zone. Such as: This area has 8 possible characters, with 36 possible entries /[a-zA-Z0-9]/. It has a fixed border with some constant pattern nearby. Show all the possible combos and then dice up the area a bunch of different ways.
On the partial constructions topic:
You have 350 of 1000 pieces of an image with some known general shape.
How much of the image can you reconstruct while still missing 2/3 of the pieces?
At the least has applications for image guessing. Also, agree on the false bank note contents, and how many people at the note shredding office are just stuffing their pockets with bank notes and then filling the cylinders with rocks? Great scam that probably almost nobody actually checks.
Why not incinerating, dissolving in acid, grinding into a fine powder, or something like that?
My pet theory is big companies first shred and after send to be burned (or recycled).
Plus a shredding machine us safer than a fire device.
But yes, paper that's shredded by a specialist paper-shredding company is then typically baled up and sent for recycling.
And whenever I need to dispose of something I can’t compost, like an old drivers license, I cut it into pieces and drip feed the pieces into the garbage over the course of a few months.
Call me paranoid but I think there will be a cottage industry in sifting through garbage once this tech gets mature enough!
You're being very, very excessively paranoid doing anything more than just cutting it into a piece or two across the ID number.
That seems like both more effort, and potentially less effective, than just burning them?
Having sensitive data compromised would make me extremely sad.
https://www.nytimes.com/1986/07/10/world/7-years-after-embas...
https://archive.ph/EVbpX
>Among the most interesting papers are shredded secret documents pieced back together by the militants that detail attempts of the Central Intelligence Agency to recruit high-level Iranian officials, ayatollahs and exiles, foreign journalists and diplomats either as paid or ''unwitting'' agents in the months after the revolution in February 1979.
https://en.wikipedia.org/wiki/Paper_shredder#/media/File:Shr...
It doesn't look like the embassy was even using a cross-cut shredder.
According to https://www.whitakerbrothers.com/pages/paper-shredders-secur... it was already up to p6-7, at least for everything I saw.
There would always be signs posted warning against wearing a tie while using the shredder.
Even if only, I don't know, 1/4 of the pieces are there, the potential to turn $13 into $4.5k isn't bad at all.
The trick, then, is to collude with other souvenir purchasers, similar to McDonald's Monopoly, so you can quickly swap your own duplicate pieces to others who need them. But unlike Mcdonald's Monopoly, there's probably no rare Park Place that virtually guarantees an instant win to whoever holds it.
The bank could do something like that. They could cut all the bills in two, and incinerate the left 60% of every single bill, so the souvenirs only contain shreds of the right 40%, thus guaranteeing that nobody can ever reconstruct 51% of a bill no matter how many souvenirs they have. But there seems to be no evidence that they're doing this.
I wonder how much the state of the art in reassembling shredded documents has advanced since then...
https://web.archive.org/web/20120126014654/http://www.shredd...
It's like revoking a TLS cert. It was once real. Now it's not.
https://www.bep.gov/services/shredded-currency-distribution#....
https://www.bep.gov/services/mutilated-currency-redemption#:...
That doesn't mean it's _not_ illegal, but it does tend to confirm my suspicion that nobody has thought to worry about it.
However, I am not a lawyer but I'd bet a court would rule that the act of shredding the currency was intended to permanently invalidate its use as currency, and any attempt to reverse that shredding via reassembly, combined with an attempt to pass off said reconstituted money as US currency, would constitute fraud. So while the rules don't seem to explicitly say you can't do it, it's implied that you can't.
Sadly it all got burned up in a fire last year.
I recommend going, if you’re ever in the vicinity of one. There will be all sorts of rare and obscure currency, plus odd things like stacks of $1,000,000 in various denominations for you to take photos with.
The lead borders follow smooth arcs, so the glass may have been ground down to fit the existing shaped holes, causing a lot to be lost.
The caption seems to suggest all of the windows were broken, but only one side of the church was reconstructed with all of the pieces. So that's 3/4ths lost there, possibly.
I could see computer vision finding the orientation of symbols and faces, and gathering similar patterns. I'm not sure how much farther it would get though.
Arxiv does this presumably because some papers have mathematical expressions in the titles and abstracts. For example https://arxiv.org/abs/2401.04991
https://www.bankofengland.co.uk/banknotes/damaged-and-contam...
The form says you need to provide ID if it's £700 or more, and they need witnessed ID for £10 000 or more for AML reasons, sadly you can't apply in person so no tearing up banknotes and popping into Threadneedle Street to do it on the spot as a tourist.
As that link mentions if the problem with your "damaged" note is that it was in a dye pack which exploded during your bank robbery, that's not an "accident" and you don't get an undyed replacement note - you're a crook, if you weren't smart enough to give a fake name and address you're getting arrested.
https://youtu.be/L9SzDFGbsFI?t=1282
https://www.cbc.ca/radio/asithappens/dog-eats-cash-1.7075889
Hong Kong Monetary Authority admits short-changing buyers of shredded banknote paperweights found to be light on cash content