Topic: I just made my first Bitcoin ATM withdrawal... 3BTC from my printer. - page 4. (Read 14497 times)

Looks like my bit cheque still has a balance. Come on people. If you did a search on this forum you will see I used the same passphrase as my last contest. It is ripe for the picking at 119 confirmations.

Very cool! 

That's right, some of the fractional coin denominations were inherited from the time when the coins were physically cut into pieces to make change.  And it's also the reason why stocks in the USA were, until fairly recently, quoted fractionally using units of 1/8ths, instead of arbitrary decimal digits.

Have you never bought or sold anything in person? If you put the coin there, you know it's there. The other party saying it isn't and running off is no different than just plain stealing it in the first place. Actually, you even have proof that you funded the address.

If that requires escrow, everything requires escrow.

You are right, but since mobile devices are usually connected to the web in some way these days, that should not be a problem. But... since this person is not answering if it works with mobiles or not... no one will know, eh?

That's a cool idea for these notes!

I will use one this Friday when giving a donation to my local hacker space. I guess I will have to fold in in half a few times before placing it in the donation jar or hand it directly to the head hacker

By the same token, you could hand him a $20 bill, and he could put it in the register, close the drawer, and then claim it was a $10, or that you gave him nothing at all.  Your word against his.  It's bad for business.  At least where I shop.


That could actually happen, but so far it has not.  It's just as possible to make real physical bitcoins and make a profit.  At DefCon, I walked around wearing a T-shirt that says "I SELL PHYSICAL BITCOINS", and was charging $15 cash for 1BTC coins worth under $9 at MtGox, selling to anyone who'd stop me in the halls.  What's better, the $6 I could make consistently by marking up the coin, or the $9 I could scam people for until I was shut down?  Meat may be tasty but you don't slaughter a cash cow.


The economics of producing holograms are such that it's a big investment to get the holographic master made.  On the flip side, if you start scamming people, you'll be left with a bunch of coin materials you can't move because people have caught on to your scam and stopped buying.

In the end, you're right: somebody enterprising could put their efforts into counterfeiting my coins and it would be disappointing.  But so far that hasn't happened, and they continue to be a great gift and promotional tool for Bitcoin.

Offline bitcoin transactions will never work unless you have strong cryoptography based hardware, and the coins are held by an escrow third party. (escrow would need to hold those funds for an amount of time until both parties hardware has checked in with the master server)

Unless you are talking about just transacting with your well trusted friends, there is always a breakdown of trust in multiple locations:

- So only the recipient has internet access in your example: he doesnt want to hand you cash until he sees the private key you are handing over actually has money in it. So he can scan it, hand it back and say it was already empty and runs away. Well he just stole the coins.
- (Well just let him scan the public key and not the private one) well ok in that case you can scam him by NOT putting the REAL private key under your thumb
- He doesnt want to hand you cash until he knows he can get bitcoins, you dont want him to scan any private key until you have cash


Lets pretend for a minute none of that matters, say casascius physical coins have a hidden private key under a hologram... Well if casascius wants to make any profit at all he has to sell them for more than they are worth. This means that if it is at all possible to make a fake, that costs less than it is worth, the market WILL get flooded with fakes.

Now there is one scenario that may work: if it costs MORE to produce a physical bitcoin representation than it is worth. In that case you wouldn't want to make a fake that costs more than its worth.  But why on earth would anyone do such a thing? They can not make profit and lose money doing it?

Love the looks!

I do like the idea of having "tear off" private keys in a variety of denominations all on the same piece of paper.  Maybe 10x 0.1 BTC tearoffs, 5x .25 BTC tearoffs, 2x 0.5 BTC tearoffs on a small one, and 10x 1 BTC tearoffs, 5x 2 BTC tearoffs, and 2x 5 BTC tearoffs on a large one.  Then, you just pull out one of the two bills and tear off the relevant denomination when a payment needs to be made.

How small could the private key QR code be made while still being readable by the typical QR reader?  Seems as though you'd need just three things on the tearoff:  A QR code for private key, a firstbits address for verifying that the address is funded, and a denomination (such as 0.25 BTC) on it somewhere to identify how much is SUPPOSED to be in that address.  If you could fit 17+ tearoffs on the same bill, it would be awesome. 

Thanks for posting this.  I just printed 8 Bitcoin bank notes.  No problems.

+100 Thank you very much! Need a while to play around with it.

That does seem to be a lot shorter. I am welcome to any standardization that you can bring to the base.

I scanned it and got U2FsdGVkX1+GmmpNCQBb+zrHyMSmAQsnk4heY+SbUssaTj+d+E2Vd5eb7D30CAdr3HFSk6hifRqQDGWputN7qz6tdyHe/2YyNV2ElfZ7cXg= but didn't make any effort to guess at the passphrase.  I am also thinking that going forward, there should be a regular format for password-protected keys (i.e. instead of something looking like 5JVpCLEMPARHYy6zVu78PR9Tc7KvLhCBLfCib3qRt1KQTxFYMsP, it would be more like 6pEKRVv4ELhVm8nGJjQNmsoLBjYDXuuZG8RAzht9Z8L6TSYJaf1 where 6p means this is a passworded priv key).

Downloading now.. will give it a shot.

OK, Windows users can download my current version of the utility and print Bitcoin notes!  It's on the menu under Tools - Paper Wallet Generator.

Binary and source is included.  https://casascius.com/btcaddress.zip

Requires .NET Framework 4.0 (which should be present on any recent Windows system).  Compiling Source requires Visual Studio 2010 (and probably will work with the free versions of Microsoft's C# compiler)

Note there is a PNG file that contains the graphic used on the notes - you can change this with any other png file with the same aspect ratio.

EDIT: I forgot it also uses the Ubuntu font, and if you don't have this installed, it will probably substitute some other font on your system.

Mike. Do you like my example that I posted above? The passphrase is pretty obvious.

There is room, and this could be implemented as one way to specify the change address.  (e.g. it includes a "changeto" section, so if the user doesn't scan a different specific change address, the changeto one is used by default, which points to the home wallet).

I'm a newbie when it comes to QR codes, but I was wondering if there's enough 'room' in the QR code so that if you had a reader that would read those QR codes on the bills and send any remaining change to an address in the QR code?  That way you could easily tear/up and throw away the original bill, and not have to worry about security issues since that amount would then be zero.  Then your change is back to your wallet (either home or mobile).
 
Obviously the QR readers (POS?) and software would have to know how to deal with the left over but then you could reprint for the next time you went out, or maybe a mobile QR maker could make your QR code when you're ready to go back up to the bar and get a refill beer (assuming you're out of your pre-printed bills)?
 
I love your physical ideas casascius, and wondered if something like this might be thought about?

Mainly because of the speed with which you can make the transfer.  You can pull out paper bills and pay in single-digit seconds, just like cash.  When everybody has a smartphone and could pull it out and wave it and pay with under 10 seconds, my proposal will be meritless.  But not everybody has a smartphone, and those that do will spend 30-60 seconds opening the app, scanning a code, initiating a transaction, and waiting for the merchant POS to detect the transaction, and those seconds are very long when you're holding up the line at the checkout counter figuring out your Bitcoin payment and wishing you just swiped your debit card.