Topic: How would you like to design a bitcoin banknote? - page 17. (Read 94802 times)

Mike, I think we all need to step back and go back to your original post.

From what we have all put in with ideas do you think you could put together a list of Standard Operating Procedures?

I think this is a little bit like putting alarms on shoes to stop you from tying them together. But I could be totally wrong, it remains to be seen how it works out in practice. I guess it could be that I use a wallet and my cash is usually out of sight, but surely others don't and will have a different set of problems than me.

I can say I would be impatient in the checkout line if the person ahead of me was having difficulty paying because he didn't cut or fold his bill just right.

just fold the bill in half when handling it.  (maybe write on the backside of the bill how much it is worth, in pencil.).

I originally mentioned a fold as a norm..

once folded it hides a QR private key underneath.. as opposed to having a private key QR on both sides..

So, a folded bill would be in practive, the defacto way of carrying it.. 

The stitching would require additional work and could not be AUTO DECRYPTED using built in QR software. So accidental spends would be somewhat avoided.

Think of it as a PIN to a debit card. Requires a little WORK to spend the money.

Unless I am completely off track.

Thoughts Mike?

What are folds going to protect against?  Someone snapping a picture of the bill and redeeming it?  Why, assuming this were to happen, they could easily splice it back together with Photoshop.  It's not as though the information isn't there for an attacker to redeem the bill, he just has to work a little bit to piece it together.

+1

http://www.perturb.org/content/foldin/

Here is the concept in action. Just click the center and you will see what happens.

And another based on the Mad Magazine concept.

Redemption concept Number 1

I was thinking about this but this would only work if the edges where cut exactly.

You would cut the bill in half. Turn one half 180 degrees and match up with the other side.



Working on a second concept right now that requires folding.

Keep in mind that people are going to have to CUT these things OUT off the printed sheet of paper so be careful of what you put twords the edges.

No. You are splitting the code, but you print both parts at the same time, onto the same film. Or in case of "split" notes, on two different films. You do not print onto the backside. That's why the medium is transparent, so there is no need to do anything on the backside. You are still thinking of paper.
That said, in case of the private key in text form, you can use a monospaced font and print every second letter in area 2 (or film 2). So even if you somehow mess up the OR code, you still can type in the privkey.

I am not quite sure which directions the notes are going. I could think of it in two ways:

1) notes that you produce yourself for purposes of storage.
2) notes that you produce yourself but intend to give away as payment.

The general problem to me, it seems, is the following: A potential receiver of the note could probably look up the amount of BTC related to the pubkey in the blockchain, but this would urge him or her to go "digital" again. The second problem is that when you are producing notes to give away, how are you going to ensure the private key on the note actually belongs to the public key printed on the note? Anyone accepting BTC in paper would have to trust you, or, in case of the website mentioned in this thread, offering paper bills with sealed private keys, the website producing them.

IDEA for 1) If we think of paper bills as means of storage, designers may want to implement steganography in order to protect the private key. I am not sure if there is a meaningful way to hide a private key (or merely an AES-encryption key to the private key) in the bill. Furthermore (I don't know if it is feasible) you could think of some type of steganographic algorithm that can be made public whilst leaving it to the owner of the bill to think of a distinctive pattern to remember and thus being sure, that he is the only one in charge of the private key. (In my head there is a picture of me in the future finding a bunch of paper notes that I created in the past and wondering if the amount printed on them is still available - if the private key is on them in clear text, you can never be totally sure.)

IDEA for 2) There are two things we are aware of. One is: There is no central authority in bitcoin that we can (or would even want to) put trust in. There has to be some degree of trust between business partners. The second is: Paper bills should be a kind of debt, but in practice they are not. Each $50 note should be a debt that someone has to pay. And WHEN it has been payed, what would consequently have to follow, is the extinction of the respective note. Let me clarify this for those who don't see my point right away: I work for someone for two hours and he offers me to help me for 2 hours when I need help. In the meantime we set up a tiny contract (a bank note) saying that he owes me a 2 hours' work. If I find myself in a situation where I receive help from a third person I might consider just "forwarding" my entitlement to two hours of work to this very person. With my tiny contract, I just created money - as long as people trust in my original "employee" to pay his debt and work the two hours for a random person. When this has been done, the contract is fulfilled and needs to be extinct. It does not happen to bank notes though, but we could make it happen to bitcoin notes.

Think of this: When you do online transactions using bitcoin on bitcoin-otc you have to build up trust. You can either do this by providing your positive transaction record (and primarily you'd go this way), but secondly you could just reveal your true identity to the person you are dealing with. This is pretty hard on the internet, because even a GPG-key that is well linked in the web of trust may be fake or might not be accepted in court, or you may provide your business partner with a fake address...
In the drafts for bank notes that we saw so far there were some having honorable persons on it. What Washington, Lincoln or whoever looks at us from our dollar notes wants to evoke is trust in the bill. Why don't we consider replacing their faces with ours? Go print a note with a public and private key plus your face on it and thus assuring the recipient that you vouch for the amount printed on it? You would not even have to go this far. Take one of the excellent drafts in this thread and add a line for MY NAME: ____ and SIGNATURE: ____. I suppose a lot of you won't like this, because you'd have to reveal your identity. But: You are only revealing it to the person your are paying. And once it has been payed, the buyer will act reasonably if he transfers the BTC on it to his own wallet because he cannot assume that he can just forward the note to the next recipient, because this very recipient will certainly (want) to put more trust in the person that is handing over the note than in the person that once created it. Therefore, the note becomes useless and can be destroyed.

Of course you could think of several attacks to this idea. One is that you could forward a personalized bill claiming to be the creator when actually you are not. This would call for id checking which is not the way to go (you might want to reconsider putting your face on the note :-) Another one is for the malicious creator of a note to spend the coins right before you hand it over to your business partner and then urge him to instantly look up the amount an the blockchain. As it will not have been processed after very few minutes, the recipient cannot be sure. I guess, though, that there are solutions to these problems that we could elaborate on. This does not need to happen here. At this place I just want to put in front the idea of personalized paper bills. It is basically just like GPG-signing private/public-keys on the internet to reveal your id to a single business partner.

edit: typo.

I agree with adding the date(s). I like this guy!

~Bruno~

I get a chrome cert warning if I try to view the first page of this thread?  Anyone else have this problem?

Thats similar to my thoughts:

Print left part of the redeem QR code on the right of side A, turn the note side-wise and print right part of the QR code, also on right of side B.

You then can half-fold the banknote to match left part to right part, forming complete QR code, to redeem. There can be some additional curvy lines guiding the correct fit.

You do not need transparent paper for this. Plus, you can torn the banknote in two parts, for redeeming you will need both parts.

Additionally, when there is single QR square for address and half-square for redeem on each side, I like the design more, its less boring.

Sorry for no images, but I am at campsite now .

I still think it is worth a shot.

+5

AWESOME IDEA!

Splitting the private key to front and back would increase security but would increase the rate of printing errors (imagine a single sided printer and multiple bills per page...multiple pages in a print job...you're just begging for mistake).

Mad Magazine has those fold pictures. You could do that with a paper wallet. If you want the code to not be easily seen, you could print with invisible, UV, or infrared ink.