Bitcoin Forum

I want to produce denominated bitcoin bills, but there is a little problem.

To do so, it seems that I would have to create a custom made tamper evident hologram to cover over the private key of every bill. This is because, while in circulation, someone could take off the hologram, copy the private key, and apply a new non-custom hologram and pass off the bill.

This is a problem because the minimum that I can get away with spending is $1500 on custom holograms. That is quite a large investment, and one that I am reluctant to make since I would mean that I would have to sell about 1,500-3000 bills to cover my initial investment (depending on the markup). It is possible, but that is quite a bit to put out to just break even in what a year or two?

I want to break even immediately and not on some future date after sinking huge amounts of time into it.

So today I thought of a solution, a very hacker-ish solution. I am not going to tell you what it is though. I would like to see if the security minds can come up with it themselves this weekend.

So let me spell out the exact problem that you have to figure out:

* Must be cheap (Less than $0.20 per unit) with less than $100 investment
* Must protect a private key on a paper bill, and be obvious when someone has exposed the private key
* Must be fast and easy to do on large sets of bills
* Must be unique and very hard for someone else to replicate

My solution is far from perfect, not exactly elegant, and I'll need to see it can handle a decent attack. But it might work.

Just tell us your solution... Why make us *guess* for it lol?

Not the type of business that all customers would trust their money to :)

Wax scratch-off like on lottery tickets, with a custom image stamped into the wax?
Oh, wait, hackerish.... Nah, I got nothing.

Do you mean maximum?  This is what I thought I understood...


This, by its nature, is the opposite of cheap.  It's sort of the same reason mining is hard - if it were easy, it wouldn't be useful.

Here is another thing you could consider for holograms.  Find someone else who is interested in custom holograms, and go in halfs.  Use their per-piece laser numbering option to mark PrintCoins.com on them, and keep the hologram very generic Bitcoin so the unmarked ones are valuable to others.  Maybe I might do it, but I am not yet sure just how I would use another hologram set.

Who knows, others might want Bitcoin holograms for completely unrelated purposes, like with MtGox or MemoryDealers or IBB or whoever lasered on their name.  Ask Roger over at MemoryDealers if he'd like a bitcoin logo hologram with lasered "ask us about Bitcoin" that he could stick on all his outgoing invoices and shipments.

If you sold Bitcoin holograms, I'd probably buy a few sheets no matter what they were.

So example, order 15,000 holograms.
10,000 of them say "PrintCoins.com"
1,000 of them say "Ask me about Bitcoin"
1,000 of them you just leave blank
3,000 of them say things your "sponsors" want on their own holograms

If you are worried about selling 1500-3000 bills.... I have already sold 1500 coins in like my first or second month, and have sold well over 3000 coins after having them out a total of not even three months.

In a real world scenario, the money circulating would wear out, and the wax would come off  :D.

I am trying to create cheap reliable mass produced physical bitcoin currency to use for daily transactions. If I could make it for zero cost and have everyone do the same, I would be happy.

I want to make bitcoin bills as cheaply as the fed produces dollars.

Hackerish doesn't have to involve electrons. MacGuiver counts, but wax wouldn't really work in wallets.

I just thought I'd interject this for people's consideration.  Metal coins have a lot more allure to me personally than paper bills. There's just something that's more tangible or the illusion of lasting a long time or something.  That's just a personal thing.  Other people might be into paper bills.  Before learning about bitcoin, I was a numismatist, but I never got into collecting bills or stamps.  Perhaps if the bills were more ornate with many levels of art on them, I would be more interested.  Just a personal opinion.

Print the public key on one side and print the private key on the other side where no one would think to look for it?  ;D

MacGyver ey?  Hackerish ey?

Strong steam-proof glue around edges of a paper flap made out of parts of old zimbabwe notes that you've laser printed a logo over plus signed with your own blood?

I actually though of printing and stickering on $1 bills. In essence the bill itself would be a hedge against either currency melting down. This would most likely get me in trouble with the SS though.

Anyway I offer 1BTC to whoever can do the best guess of what I am thinking of. This will be my judgement as to who did the best, and I might spit it up among multiple people if they each guess different elements.

Deadline Monday, noon PST.

I might though an extra BTC to someone who comes up with a better idea that I decide to go with instead.

Don't read too much into my mention of MacGyver. I just wanted to illustrate that hacking isn't just about code.

Here's an experiment to try. Print key codes on fiat currency and release it back into the wild. Wait and see how long it takes before the amount is redeemed. This may help spread awareness.

THat is actually freaking brilliant.  And you could take back the money if too much time went by.

A lot of people would need to be doing it for anyone to notice...there are a lot of pieces of paper out there.

And it would be somewhat difficult to print a unique code on each bill, for most people.

I have an idea, what about sponsored bills?

I would highly subsidize the cost for bills printed with my BitInstant Logo on it, that I can sell, give to friends, or anything like that.

Lets make it happen!!

You are getting warmer. I have a plan similar to this.

LOL warmer to what? I wanna do this now!!  :D

How are they going to spend their paper Bitcoin on your website?

I think he's looking at them as an advertising method

They aren't. I can sell, give to friends, or anything like that.

Heh, I was thinking you were a retailer. It actually makes a lot of sense for exchanges to have printable bills. I'm surprised mtgox hasn't thought of this for their redeemable codes.

I'm sure they have, but think about it. Going from an eCurrency to a 'MtGox Real Currency' that theoretically people can physically buy and sell which can become a legal issue.
Think about if I opened a real store and only took MtGox Dollars, or TradeHill Kroner (Love the sound of that) I think the exchanges could get mixed into some legal issues.

I'm not sure of the EXACT legalities, so if anyone else has more insight...please contribute!

I think it is technically illegal to print or write on US currency, although it's probably not enforced very often.

At bit of searching finds:


Still looking for the original source.

I thought the same thing, but WheresGeorge.com does it. However, after looking into it still illegal.

"Defacement of currency is a violation of Title 18, Section 333 of the United States Code. Under this provision, currency defacement is generally defined as follows: Whoever mutilates, cuts, disfigures, perforates, unites or cements together, or does any other thing to any bank bill, draft, note, or other evidence of debt issued by any national banking association, Federal Reserve Bank, or Federal Reserve System, with intent to render such item(s) unfit to be reissued, shall be fined under this title or imprisoned not more than six months, or both. "
http://www.moneyfactory.gov/historicallegislation.html

Don't ever mess with the us dollar or create any that can be confused with it. It's the fed's product and they don't take kindly to people messing with. The laws are vague enough that anything you do to the dollar is risky.

Don't get bitcoin involved either.

I love what you are trying to do. I will add this into the equation.

If talking about US currency as a fiat currency, it is only illegal if you edit the money with a fraudulent intent, or use the modified money fraudulently. Like adding two zeros after a one (making it 100) and using it as a 100$ bill. That's how the 'where's geroge' thing isn't illegal.

create a bitbill for 1.00 btc. Have a DB at trusted central server.

on bill, have 12 scratchoffs. This particular bill has 12 A-z on the scratchoff, while under the scratchoff has A-z as well.

You hand the bill to someone, he puts in the 12 char code at central server to confirm 1.00 btc. In this case, it is:

A B C D E F G H I 5 4 3

He then secretly scratches off 1-12 boxes (his choice), which reveal a new code. In this case he scratches off 2 to make the new code, and tells the server what he did:

A B Q D E F G 8 I 5 4 3

The central server now needs this new code to redeem. Even if the bill was compromised, the first person wouldn't know what was scratched off.

W/O scratchoffs, you can just keep appending a prior code. Maybe each new merchant could attach a new QR code (sticker/print) w/20 random chars.

I'm still trying to figure out how to make it so that it can't be copied to look exactly the same, numbers and all, so two physical 1BTC bills exist for one digital one. That part actually worries me, that we may end up with 21M Bitcoins, and maybe 40M total Bitcoins including physical ones in circulation.

Take this idea and run with it. Rip a bill in half and print bitcoin on them.

Would printing BTC on them be 'mutilating'?

Defacing, yes... illegal

Unfit to be reissued? If you use holograms I'd think yes. Otherwise?

Doubtful they would get destroyed immediatly, here in canada, they get taped (poorly) and stappled back together and still go through the ringer and get spit out of a bank machine..  I work with the banks and their cash, its amazing how horrible they get before being set aside to be destroyed..

Don't you guys have the polomomer based paper?

You could use 100s of the failed currencies of the world and get them for less than a penny each.  Zambia has some beautiful currency.  They even sell them on ebay.

But this doesn't solve the problem of the BTC bills being easy to forge - if you can buy these old notes cheap - so can someone who wants to copy your note and issue it without any value inside.

Yes, "double spend" by physical duplication is impossible to detect reliably in physical transactions with no corresponding block chain record.