Physical Bitcoin Check Generator

[error]

So let's see if I understand it right.

You handle me one of those "checks", I go to some address input its serial # and the site tells me how much is in that "account".
I scan the QR-code containing the PK and that's it.
So if it was already "cashed-out", the serial # will tell me "nill", "zero".

right?

Yessir. That's absolutely correct.

So, in that case, the merchant could deny purchase.

You still have not addressed the fatal flaw here: Merchants will, sooner or later, stop verifying them at point of sale unless there's a technical requirement to do so. They will stop because they will trust the notes, because for a long time they all verify OK. At that point, I come along and pretend to be texting on my Android while I'm really snapping pictures of other people's QR codes and sending the Bitcoins to myself.

Worse, this system practically requires merchants to not only verify them at point of purchase, but to cash them out; otherwise an unscrupulous employee at the till can just take all the QR codes for himself. This is just too risky. I could not imagine accepting these as a merchant as-is.

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[Anonymous]

Wait a second, why do you need the public keys on the checks?

You don't. However, I prefer to give people an alternative to scanning the private key. You want to avoid copying the private key as much as possible.

[Anonymous]

You still have not addressed the fatal flaw here: Merchants will, sooner or later, stop verifying them at point of sale unless there's a technical requirement to do so. They will stop because they will trust the notes, because for a long time they all verify OK. At that point, I come along and pretend to be texting on my Android while I'm really snapping pictures of other people's QR codes and sending the Bitcoins to myself.

I don't believe merchants will be naive enough to start trusting them as-is. It simply isn't in the market's best-interest. Your ability to describe such a scenario so quickly simply proves it won't happen.

Why don't you start snapping pictures of people's credit cards then? I wish you luck.

Worse, this system practically requires merchants to not only verify them at point of purchase, but to cash them out; otherwise an unscrupulous employee at the till can just take all the QR codes for himself. This is just too risky. I could not imagine accepting these as a merchant as-is.

Employees have and can steal actual cash. There are systems to prevent this and they will be certainly made if the need arises for my checks. I don't see anything wrong with merchants just cashing them out digitally and destroying the note. It's actually more convenient in the end but still allows the average joe without a fancy smartphone to use Bitcoins anywhere.

[Anonymous]

We can list "what-ifs" all day. What if people mistake these notes for receipts and just throw them away? Honestly. : P

Anyways, I like the questioning-attitude.

[error]

(Quote elided)

You're assuming people will act perfectly in conformance with your protocols, and I am saying that the other six billion of us live in a world where that just isn't going to happen. No human is perfect, except perhaps yourself. When things go wrong -- and they WILL, despite your protestations -- it's your notes that will take the blame in many people's minds. (Whether that's fair or not is irrelevant.)

What I really don't understand is your apparent unwillingness to consider any security issues with respect to your notes. This really does not inspire confidence.

[Anonymous]

(Quote elided)

You're assuming people will act perfectly in conformance with your protocols, and I am saying that the other six billion of us live in a world where that just isn't going to happen. No human is perfect, except perhaps yourself. When things go wrong -- and they WILL, despite your protestations -- it's your notes that will take the blame in many people's minds. (Whether that's fair or not is irrelevant.)

What I really don't understand is your apparent unwillingness to consider any security issues with respect to your notes. This really does not inspire confidence.

On the contray, I embrace the fact we are free-thinking (or sporadic to those who deny freewill) individuals. Yes, failure will occur just as wallets are stolen and how other heinous crimes occur. You could say life it self has serious "security issues".

I don't know how you expect me to fix facts of life. I can't prevent people from abusing something they inherently have physical access to.

Unless there are other "flaws" that haven't been covered, I think I've done all I could in reducing risk as much as possible.

[BCEmporium]

This would be a good start for an idea to print it. QR-Code stays under a scratch layer.

[Anonymous]

This would be a good start for an idea to print it. QR-Code stays under a scratch layer.

Haha, wow, thank you.

Hm, we could sell such notes separately for those who need that layer of security, since most people aren't willing to paint pieces of paper. There is also the possibility of Kiosks, but that's an expensive venture that won't have any return until far into the future.

Wonderful, nice concept.

[Ryland R. Taylor-Almanza]

This would be a good start for an idea to print it. QR-Code stays under a scratch layer.

Love it!

[error]

On the contray, I embrace the fact we are free-thinking (or sporadic to those who deny freewill) individuals. Yes, failure will occur just as wallets are stolen and how other heinous crimes occur. You could say life it self has serious "security issues".

I don't know how you expect me to fix facts of life. I can't prevent people from abusing something they inherently have physical access to.

Unless there are other "flaws" that haven't been covered, I think I've done all I could in reducing risk as much as possible.

But you have not done all you can (see the nice mockup directly above). I don't expect you to fix "facts of life" (whatever that means). As a potential user, I do expect some level of security against the most obvious attacks. As it stands, your system is unworkable in the real world. I expect the market will reject it outright.

[Anonymous]

On the contray, I embrace the fact we are free-thinking (or sporadic to those who deny freewill) individuals. Yes, failure will occur just as wallets are stolen and how other heinous crimes occur. You could say life it self has serious "security issues".

I don't know how you expect me to fix facts of life. I can't prevent people from abusing something they inherently have physical access to.

Unless there are other "flaws" that haven't been covered, I think I've done all I could in reducing risk as much as possible.

But you have not done all you can (see the nice mockup directly above). I don't expect you to fix "facts of life" (whatever that means). As a potential user, I do expect some level of security against the most obvious attacks. As it stands, your system is unworkable in the real world. I expect the market will reject it outright.

Well, I have yet to see any objective reasoning for rejection. Feel free to provide.

I guess you don't like credit cards or checks, eh?

[Anonymous]

We could simply have a fold of paper that you can seal over the QR code. That solves that.

[Sultan]

If I were to use this, I'd go for the scratchpad rather than folded paper! Just a personal preference if there were competing services.

[ColdHardMetal]

If I were to use this, I'd go for the scratchpad rather than folded paper! Just a personal preference if there were competing services.

Scratchpad looks cooler but then it can only be transferred once. With a fold over cover it could go through multiple hands before being redeemed.

[rebuilder]

Scratchpad looks cooler but then it can only be transferred once. With a fold over cover it could go through multiple hands before being redeemed.

Surely not? The QR code would only be needed to access the BTC in the block chain - when that is done, the printed note becomes invalid.

One thing to keep in mind is this is likely to be highly illegal pretty much anywhere. At the very least any government would want you to register to handle financial transactions. At worst, they'll see this as a paper currency issued by Atlas. CYA.

[ColdHardMetal]

Scratchpad looks cooler but then it can only be transferred once. With a fold over cover it could go through multiple hands before being redeemed.

Surely not? The QR code would only be needed to access the BTC in the block chain - when that is done, the printed note becomes invalid.

Yeah, that's true. If you can just check the balance is there with the serial number then the scratch part is safe..

[ribuck]

Also, 20 - (20 * .005) =/= 19.9 BTC, ribuck?

In your original post you wrote 0.005%, which equals 0.00005, not 0.005.

[Anonymous]

Dont make them look anything like fiat or write "cash" or "bank" on them.

I like the scratchcard idea.

[N12]

Dont make them look anything like fiat or write "cash" or "bank" on them.

I like the scratchcard idea.

Second that. A scratchcard would be a fine solution. Also, people like scratching them up … At least I do.

[Anonymous]

Dont make them look anything like fiat or write "cash" or "bank" on them.

I like the scratchcard idea.

Second that. A scratchcard would be a fine solution. Also, people like scratching them up … At least I do.

Its some peoples favourite past time. Sitting down at the cafe drinking a coffee while scratching a 2 dollar ticket