Topic: [ANN] bitaddress.org Safe JavaScript Bitcoin address/private key - page 29. (Read 153052 times)

Nice.

Note: For the top-right denomination, you may try out:

0.25__

That's quite good! Here's  what my notes might look like:




Thanks again!

Next update - 3rd version - and probably my last one!




Only change of the content of the zip file is the HTML file - other files like documentation have not been updated (not necessary).

Changes:
* Fixed the alignment to right-align for the number at the top-right.
* Added the option of printing a larger priv key QR code that can also be sealed
   (but not with hologram then, since such large holograms don't exist)
* Added support (tooltips onMouseOver for the thumbnails to find the right RGB color codes if you do not want to print BLACK denominations. Colored numbers matching the color scheme of the note's design look just so much better.
* Added optional "glowing" feature, also matched to the color scheme (see screen shot above, the orange "glowing" behind the numbers).
* Overhauled the GUI
* Help buttons with detailed explanations are now everywhere around.
* Tool tips on mouse over of the thumbnails...
* Again more "intelligent" behavior when the private key and address do not match or are
  invalid - both in terms of dialogs and actual behaviour.

@ all: I think that's all from my side now. I cannot spend that much time for the future. I am sure it is very useful for the community.

@ pointbiz/bitaddress.org: I think you can assume that I will not do any major changes any more, and no changes at all after christmas and next year at least for quite a while. So if you intend to work on merging it into the mainstream, you can be assured that I will not "interfere" next year with yet another update... ;-)


PS: And here is the link to the latest 3rd version (9.8 MB): http://dl.dropbox.com/u/18219492/Bitcoin/bitaddress-org_Michael_S_enh_v3-zip.zip

UPDATE 30 Nov 2013: Get Version 10 (GPG signed zip file) of my tool with mBTC denomination support and some cleanups! (11.8 MByte)

Great idea to give out tips! I had the idea with expiring bitcoin vouchers already, see my post #318, but I did not quite know were I as a private person could apply it. But tipping (also) with bitcoins (in the form of expiring vouchers of course) in restaurants etc. is an excellent idea!

By the way, yesterday I met with two friends in a pub. For one of them, I handed over the casascius coins to him that I ordered for him together with my own order (and which he was very happy about of course). And then, I also put this bitcoin-demo-note on the table, and this triggered a good discussion also with friend #3 (who is not into bitcoin yet). It is fascinating that having something tangible in one's hand is just a different thing than just having the bitcoins electronically. It gives another level of inspiration and triggers much more vivid discussions, because, while you are discussing, you can take the coin or the bill in the hand, turn it around, feel it, see it, it is simply inspiring. I guess this lies in human nature.

That was exactly the idea of my sample screenshot that I had posted here (look what is printed in the center of the bitcoin note   )  --> https://bitcointalksearch.org/topic/m.1383041

I did fulfill your other request with the larger QR code - now everybody has the choice. I also and introduced colors for the denominations and optional "glowing" effect behind these denominations. I also overhauled the GUI again quite a bit. For example, Now there are "?" buttons everywhere with lots of explanations.

Unfortunately, for this unfortunate and unnecessary narrow spacing between the bills I did not find the corresponding setting in the source code. Maybe I am just too tired... Note that I am an absolute beginner in JavaScript, I learned everything while doing it - in the end any programming language is built on logic, so it is possible... takes  time though...

I will post the update in a few minutes...

Maybe they will say WTF is this and Google it.  Or maybe they won't.  I figure if they don't, in the end, all I'm out is 1/3 of a piece of paper.  They also might shove it somewhere, and 3 months later hear about bitcoin from somebody else, and realize "Oh wait I have some of that".

Just because I give something away doesn't mean I don't value it, it just means I'm willing to share.  If I tip with bitcoin, it's usually on top of a normal fiat tip.  I already tip well for good service anyway (20-25%), here in Utah that's relatively exceptional (seems any time I go out with anybody, everyone's got it wired in their brain how to calculate 15% to the penny), so I have little reason to believe that people would assume me giving it away meant it must be worthless.

If you don't value that 0.1 BTC and are willing to give it away, then why should the person who receives it believe this piece of paper from a complete stranger would be something of any value either?

I recently experimented with a couple different approaches for this.

One that I tried just once failed but I plan to try it again with better results.  What I wanted to do was to let the person "do work" to earn the funds.   About the only "work" I could think of was bitZino blackjack or roulette.  After the person plays a few rounds, they get the payout (I'll withdraw it to their paper bitcoin).  

My first attempt at this failed because I didn't have good enough internet connectivity when trying to demonstrate it.   (My next try I might use http://KingCo.in instead for the form of "work" with someone at random as there is no need for that person to know how to play blackjack and KingCoin's game is more visually entertaining.)

That's a great idea Mike! I've been thinking about just giving people bitcoins but I've been held back by the thought that I'm wasting my money. This way, if the bill doesn't get spent by dec 31st 2013, I'll sweep all that's left back to my wallet print new ones and hand them out again. Great, great tip! Bitcoin Faucet offline, IRL

Michael, another feature request if I may: could you set the spacing between the 3 bills on the page a little bit wider? just 5 milimetres more, it's going to make it far easier to tape, thanks. I can't wait to get started.

Here is a totally legitimate reason why one might want to print bills out of known private keys.

I frequently give out 0.1 BTC with restaurant tips and to strangers.  But I know that much of the time they will probably just throw them away.  It would be nice to only give up 0.1 BTC to those strangers who really end up wanting it.  It makes it more affordable to give bitcoins to everyone, and gives them a reason to find out what bitcoins are right now, before the voucher expires.

In such a scenario, it's reasonable to put an expiration date on the voucher.  The terms of expiration are that the voucher expires if they don't redeem it, but if they do anything with it (such as send it to their own wallet), then the bitcoins never expire.  Then after the expiration date, you just swipe all the unclaimed bitcoins back into your wallet.

Being able to paste a list of pre-generated private keys makes that really easy, because eventually you'll need that same list to import into the wallet of your choice.

I second what Mike is saying. A full size qr code, covered with a full size plaintext square of the privkey would be excellent. Everything would be taped on both sides with clear tape that is the width of the bill, and a black paper square sandwiched in between. The fully-taped in bill would be more durable than the plain paper/hologram combo, and with pattern printing on the back it should be safe enough for the small amounts of bitcoins likely to reside on them. I for one am not going to go the hologram route. Oh, also, it would be nice to have a cutting guide a couple of mm larger than the pattern itself to make it easier to cut the bill open with scissors and reveal the qr code/privkey when the time comes to redeem it.

All that's required is to mod the file to not print the privkey in plaintext on the bill with the big qr, and have it print a same-size plaintext privkey box on the side. I've no idea how hard it would be to do this though.

Michael, it would be great to see this. If it's not too much trouble, could you come up with a secondary version of your mod to fulfill these requirements? Pretty please?


Thanks!

PS: I want to hand out a bunch of these for Christmas

I thought I saw a checkbox that re-enabled the original size when I played with it and this wasn't even an issue?  By the way, thanks for this fantastic contribution to the community!  This alone takes paper notes a huge leap ahead.

Just thought I'd provide some input: that 36% margin in size is dependent on a lot of things that are not guaranteed.  The smaller the code, the more damage if something happens to it.  Laser toner is notorious for flaking off certain kinds of paper when creased or for no reason at all.  Someone else's printer may have poorer print quality than yours, or may have an ink cartridge that leaves black or white streaks, or may be using a print technology (e.g. dye sublimation) that makes beautiful photographs but has a hard time with black-to-white edge transitions.

On the other hand you might have a perfectly readable QR code but a user can't read it because his mediocre smartphone can't focus on the code as close as it needs to be for the smaller dots to be made out.  Quite simply, there are advantages to letting the QR code occupy the available space rather than leaving white space the user doesn't want on the assumption that there's no advantage to do it any other way.

Thanks a lot for the tip! My first earnings in BTC  

Interesting to know about OSX Firefox... maybe it would be good to be able to move the position of the denominations up and down a little from the user's side. But this is CSS based, which is static as far as I know (I don't want to use php etc. of course, this should remain purely html&javascript based), but maybe I do it by defining several style sheet templates (e.g. 5 or so) and then select based on some user input parameter one of them to allow more optimum positioning of the denominations....

Good idea - I will do it like that!

Anyway, the usage of "___" will be needed if one wants to move the number a little away from the BTC symbol, especially for one-digit denominations it may otherwise look a little imbalanced.

Is there no way to use text-align right to avoid all this?

I think you've covered my questions quite well Michael, thanks. Tip sent.

It was Firefox 12 on OSX 10.6.8. Safari doesn't render well because I have the min font size set to 12, FF is "stock".

(In the IMG tag of your post, I changed the "https" to "http" and more importantly the "www" to "dl" such that your public dropbox image gets displayed here!)

Here's how you can get around it:
In the field "Denomination (top-right)" you can enter
   "____________5", or similarly
   "2>_________5", or similarly
   "4>_______.
I thought that this was clear from the example of the pre-configured content in this field, which is
   "_500".
This was actually the reason for me pre-configuring it with that content - to lead the user towards using the input correcty.
But maybe I should enter a note saying that "_" gets converted to non-removable " ".

You can put any amount of "blanks" there to move the denomination to the right. However, since more than one successive blank gets removed in HTML text rendering by the browsers, you enter underscores instead of blanks, which are converted to non-removable space (" " to be precise) internally by the tool, so non-removable blank characters ( ) get rendered. So you have full control to shift the denomination as much to the right as you like.

The "cutting guide" is already there! Just cut out along the line! (for the "black" squares: you may decide for yourself if you cut out closely along the solid black square or along the outer thin line.)

Note that the "plain-text private key square" does NOT have the same size as the QR code but it is intentionally a little larger than that (ca. 18 mm as opposed to 15 mm)! The reason is that it should PROTECT the QR code when you cover the whole thing with a hologram sticker. If it was exactly the same size, it would be very very difficult to line up exactly, and you would very like damage the QR code with the hologram sticker if you assemble your note.
That's why some margin in size is needed. The hologram then has a size of 2.54 or 2.85 cm (depending which one you purchase), i.e. there is still a lot of space left at the edges such that the hologram can be properly attached.

So you see - everything is thought out well! :-)

Request rejected! ;-)
The reason for plotting SMALLER QR codes in the first place was to be able to cover the QR code with above sized hologram that can be purchased easily. With the original sized QR code that is not possible, because even larger square holograms are not readily available on the market  - the largest standard sizes are 1 inch and 1.125 inch, to what I know (and if they were available, even larger ones would not look nice).

About the ease of scanning: The 15 mm size is well enough for scanning. I tried it out myself: I printed out QR codes of smaller sizes as well (and I have a rather old and cheap laser printer Brother MFC-7820N), and my cheap smartphone "Samsung Galaxy Ace" could scan it very well down to a size of 11 mm, so there is a 36% margin in size for the 15 mm chosen! Also the error protection was good: When I drew a few lines across the 15 mm QR code, the smartphone was still able to detect the right code, so I am convinced that 15 mm is a good choice. And if it still does not work to scan it, you have still the plain-text private key in the sealed pocket as fall-back, so ...

...again - everything is thought out very well! :-)


@fivemileshigh QUESTION: What browser and operating system did you make your screenshot from? (I used firefox 3 on Linux and firefox 13 and 14 under Windows - everywhere same result). It seems that your browser positions the denominations a little bit higher than my browser does. In my case the denominations at the bottom-left and top-right are exactly lined-up with the respective BTC symbol.

Bug/feature request:

when printing the non-tamper-proof version, the top-right denomination covers up a bit of the plaintext private key, see example:



Michael, could you also make another change? I would like to see a cutting guide (plain square box) around the plaintext private key, to make it easier to cut it to the same size as the qr code box. I would also like the qr code be left at the original size, for easier scanning. Along with printing the back of the bill with the provided pattern I would think this would be plenty tamper proof enough for the small amounts likely to be found on these bills. I would tape the whole face of the bill with wide scotch tape, like you did with your bill earlier. This is likely as tamper-proof as the hologram idea, and probably more durable overall.

Really paranoid types like me can also place a small piece of foil or other opaque materials in between the plaintext and qr code to provide extra protection against scanning with a strong light. Just enough of the qr needs to be blocked out, not the whole thing, right?

How would this attack be better for an attacker who has the means to make new bills versus just making n copies of a new bill, funding it once, and spending it in n different places?  Why bother matching the key of some other bill?  It is just a random number.

I wasn't referring to someone making multiple copies. I meant someone who received the printed bills could remove any tamper sticker or overlay, remove the balance, then print a new bill using the same private key, apply a new sticker or overlay, and pass the bill off as original. It wasn't as easy to do this before because they would need to modify the code the use a given private key.

My only point here is that people should not trust bills like this at face value even with tamper proof stickers. You may as well just use pokemon stickers or whatever is handy.

The same could be said for coins if the tamper proof stickers were easy to get and print a first bits on but I think that is difficult.

Someone could also just do Copies: 2 in the print dialog or any other number.

Preventing someone from supplying their own keys isn't going to enable anything not yet possible