[ANN] VisualBTC - Android-based hardware offline wallet using animated QR codes

[drazvan]

Hello everyone,

I've just released VisualBTC, an Android-based offline Bitcoin wallet that uses animated QR codes to send/receive transactions and synchronize with the Bitcoin network.

A quick YouTube video demo is available at http://www.youtube.com/watch?v=m9-mbb0qc9I .

The idea is very simple: use a cheap 4.3 inch Android tablet with a capacitive screen ($50 in singles, bought from Amazon UK - http://www.amazon.co.uk/gp/product/B009HY6BXU/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=B009HY6BXU&linkCode=as2&tag=ver02-21), disable its WiFi connection and transfer data only over animated QR codes (that is split any long strings into smaller chunks and animate those chunks as separate QR codes).

The application communicates with an HTML5 + JavaScript page that requires no server side components (QR code scanning and generation is all done in JavaScript, webcam interaction is also done locally via getUserMedia(), blockchain data is read and transactions are posted via blockchain.info directly from the page via JavaScript. It works with Chrome, Firefox and Opera. It does not work with Internet Explorer, sorry, at least not yet.

The private keys never leave the tablet and it has no Internet connectivity whatsoever, so it cannot be attacked from the Internet.

The wallet application itself has been designed to be extremely simple, something even your grandma would be able to use. It only has two buttons: Pay and Sync.

Clicking Pay allows you to scan a QR code (standard format, bitcoin:address?...), then assembles a transaction, signs it, then shows an animated QR code with the transaction data. Showing that animated QR code to the webcam at http://www.visualbtc.com/ posts the transaction to the Bitcoin network.

Clicking Sync shows a QR code that you once again scan at http://www.visualbtc.com/ . It then shows you an animated QR code of your unspent outputs. You scan that with your wallet and it updates the balance and the internal list of unspent outputs.

Private key export/import is available using a special "Advanced mode" (hint: click 10 times in quick sequence on the QR code on the main page ).

This first release is free but is currently limited to 1 BTC maximum wallet value and 0.1 BTC per transaction. You can remove this limitation by paying (from the VisualBTC wallet itself) 0.25 BTC to us. You can also send donations and tips to 1VBTCXXcYmUCzYUcmdcakSGdyavUnByFF.

You can test this on any Android phone or tablet with a camera or you can buy that Pocket Scroll tablet I suggested above (full disclosure: it's an affiliate link, we get some $2.5 for each purchase ) - for $50 it's a great little device, 5-point capacitive screen, camera, WiFi, etc.

Suggestions and questions are very welcome! It's an early release and we do plan to improve it, but I wanted to get some feedback first.

Enjoy!

Razvan

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[Mitchell]

DAMN, that looks great. Amazing idea and well done. Good job dude!

[coincepts]

Super cool! Thanks for your hard work!

[drazvan]

Thank you!

One more thing that I think makes this solution very interesting: this is truly a standalone wallet that requires absolutely no software installed on your computer. You can pay securely in an Internet cafe or anywhere you can open a browser to http://www.visualbtc.com/ . Also, merchants do not have to alter their payment flow in any way. Most (if not all) already display the QR code corresponding to the payment request (so that you can use the standard Android Bitcoin wallet to pay), so all you need to do is scan that same QR code with VisualBTC and then navigate to http://www.visualbtc.com/ and visually post your payment.

Even for in-store transactions, they just have to display the QR code for the payment request, then scan your animated QR code transaction and broadcast it to the Bitcoin network.

[runeks]

Looks cool.

Is the application open source?

[drazvan]

At this point the app is not open source. We're trying to figure out the best way to monetize this. The animated QR code protocol will be opened to allow third parties to verify we're not sending the money somewhere else.

Anyway, the server-side app is just JavaScript + HTML5, so you have all the source right there. You can check what it's doing with the scanned code, monitor the network connections to see that it's only going to blockchain.info and even save it locally and run it, to make sure it's still available in 1, 5 or 10 years. It's just a webpage + some AJAX.

[dnaleor]

checking it out, maybe i'll order

[drazvan]

BTW, I know I mentioned it in the first post but people keep asking me this, so here it is again: you are not locked into our solution and you can also import your vanity addresses into the wallet. There's an "advanced mode" that you can trigger by starting the app, then clicking in quick sequence about 10 times on the QR code on the left. The screen will turn red when it's in advanced mode, so you can't miss it. There's an "Export private key" option that shows a QR code with your private key that you can scan and import into any other wallet and an "Import private key" that scans a QR code of a vanity (or existing) key and replaces the one in your wallet. Warning: importing a new key overwrites your existing key and any existing funds are lost if you have not exported the old key to another wallet. So if you have any BTC in your wallet, export the key first before importing another one.

I hope this clarifies things.

[molecular]

that's pretty cool, dude!

[btceic]

i have a 3g and a 3gs iphones that i am not doing anything with, would this work on either of those?

[P_Shep]

Fairly big issue with the device posted up there... has no camera.
In fact there aren't many small tablets with cameras. Seems to have to go into phone territory to get a camera.

[bitpop]

Why would he recommend a tablet with no camera?
What about backup?
Settings menu does not work on my note ii.
I think it is way too early to be so aggressively monetized.

[drazvan]

Fairly big issue with the device posted up there... has no camera.
In fact there aren't many small tablets with cameras. Seems to have to go into phone territory to get a camera.

It does have a camera on the back, what are you talking about??? I have one right here and you can see it taking pictures of the laptop screen in the Youtube video I posted above, where did you expect the camera to be?

[bitpop]

Lol

[drazvan]

Why would he recommend a tablet with no camera?
What about backup?
Settings menu does not work on my note ii.
I think it is way too early to be so aggressively monetized.

I'll check the Settings menu on my Note II, I have one as well. What happens when you click 10 times or more in quick sequence on the QR code? Does the screen not go red (indicating config mode)? There is no "menu" per se (if you press the Menu key from within the app), there really aren't any settings in the app. Let me know what you'd like to set, maybe a Settings menu is needed after all.

And how is it aggressively monetized? It's FREE! As long as you keep your balance below 1 BTC and transactions below 0.1BTC. So it's free to try it and for small transactions and costs about $25 (at the current exchange rate) if you want to store more than 1 BTC or make larger transactions. I love it how people don't even blink when they hear that the Trezor costs $100 for the standard and $300 for the metal one but run for the hills when we charge nothing for small transactions and $25 for heavy users... .

[drazvan]

i have a 3g and a 3gs iphones that i am not doing anything with, would this work on either of those?

It's an Android app, so no, it won't work on the iPhone (any iPhone).

[P_Shep]

Fairly big issue with the device posted up there... has no camera.
In fact there aren't many small tablets with cameras. Seems to have to go into phone territory to get a camera.

It does have a camera on the back, what are you talking about??? I have one right here and you can see it taking pictures of the laptop screen in the Youtube video I posted above, where did you expect the camera to be?

Really!? I don't see where it's mentioned on the page... and I've looked VERY carefully. I don't put it beyond Amazon that they simply don't mention it! And there's no pic of the back side.

[drazvan]

http://www.storageoptions.com/products/scroll/tablets/scroll-pocket - go to the Specifications tab. Backside is here: http://static.scan.co.uk/images/products/1977867-d.jpg

[P_Shep]

Wow, even on that page I had to go to the specifications page to see the camera mentioned!
(Mind you, 0.3 mega pixel is quite embarrassing )

So it's not too bad then, but i'll probably wait another 6 months and see what's state of the art. This sort of device does make for the perfect hardware wallet.

[drazvan]

Well, you won't be using it to film your next Oscar-winning motion picture, 0.3M is good enough to read the QR code from the screen of the laptop and that's all you want it to do. That's why we suggest a cheap dedicated tablet for this and not your everyday tablet or smartphone - it's tempting to start adding stuff ("it can't hurt to have Angry Birds on your wallet, can it?") if the hardware is more capable. But if all it can do is be a wallet, we hope people will stick to that.

We are working though on a smartcard-enabled version that will move the key generation and signature to the smartcard, allowing you to use it in a regular Internet-connected smartphone (with some "secret sauce" to allow the smartcard to talk back to directly to you and make sure that your phone is not full of malware and asking it to sign 1000 BTC transactions to some random address).