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1  Bitcoin / Development & Technical Discussion / Bitcoin Credit Cards: How to create a POS device? on: March 13, 2013, 05:17:00 PM
Currently, to purchase something with Bitcoins in a local brick-and-mortar store, the merchant usually has a sign with a QR code on it which is their receiving address. It's then the buyer's responsibility to have a smartphone/tablet/whatnot that can scan that QR code and generate the transaction to pay. Conversely, paying with credit/debit card, the buyer only has to present their unique identifier (account number) and it's the merchant's responsibility to have the cash register/POS technology to generate the transaction. While the number of smartphone users is increasing, that reversal of roles as to who generates the transaction is a little daunting to those used to paying with credit/debit cards.

So can that be reversed for Bitcoins? Right now instead of having the merchant show their public address to be paid, the buyer could present a QR code of a private key to the merchant, and the merchant could have a "cash register" app that uses that Private Key to generate a transaction to the merchant's account. The buyer would have to trust the cash register app to not hang on to the private key long-term, and not create additional transactions beyond what's agreed upon, but that's what we as buyers do every time we use a POS device for a normal credit card.

The issue is the handling of a printed QR code with a private key on it. If the shop has security cameras (or an enterprising paparazzi with a massive telephoto zoom is lurking nearby), a recorded photo of your private key QR is now in the hands of people you may not trust, which effectively means many more people got access to your Private Key than you intended.

How can this be solved? I had a few ideas:
  • conductive ink: With the rise of touch-screen tablets, there's a few vendors out there who are starting to market physical items you purchase that interact with your digital app. Monsterology by Nuko is one example: You buy physical cards that have visible ink showing information about that particular critter, but there's additional, invisible, conductive ink on top of that (presumably using TouchCode technology) that the touch-sensitive devices can decode and read the unique ID of the card being presented. So using visible ink, print the Public Key on a piece of plastic, and with conductive ink, encode the private key on top of it. Then a tablet/phone app can be written to interpret the key without broadcasting it.
  • invisible ink: There are some inks that are visible (opaque) in the infrared spectrum, but transparent in the visible spectrum. Most cameras can see infrared, but filter it out; if the merchant had a modified webcam to record only in the infrared, the private key QR code could be printed in invisible ink on a blank back of a bitcoin credit card, which would prevent others from casually observing it. However, that enterprising paparazzi could also modify their camera to record in infrared and still grab your private key.
  • mag stripe encoded: This is the way normal credit cards do it, so would feel very familiar to users. However the issue becomes decoding it. Mag-stripe-scanning hardware addons for smartphones are starting to emerge (like the Square scanner), but those have proprietary apps associated with them, which are tailored toward Credit Cards, and not customized cards. I know in major US retail stores, some have their own "in-store credit cards" that aren't Mastercard/Visa-affiliated (you can only use them in that store), but the POS (point-of-sale) scanners in that store know the difference and can handle normal mastercard/visa cards and the special in-store ones.
It seems that the conductive ink or mag-stripe encoding would be the best solutions, if they could be implemented, which is where I'm stuck, and wondering if there's anyone here who knows more. The TouchCode website gives information about the features of their product, but no pricing or technology specifications. I might just email them for some introductory information, to see what they would offer. If there was a third party who did the printing of private keys onto the cards, there would have to be a degree of trust there that they don't keep a record of the keys after they leave their factory.

For mag-stripe encoding, you can buy devices to encode whatever you want on a mag-stripe, but I'm lost in finding resources for implementing a new type of financial card. How do retailers implement an in-store credit card for their POS devices? What programming language/certificates need to be used to load a new type of financial card on a POS device? For mobile scanners, I found a few threads (here and here), which point to a few vendors that have API access to their hardware, but most are still focused on standard credit cards and handling the payment for you as a credit transaction, and give you the data off the card assuming it's in standard financial card (ISO/IEC 7813) formatted. Is there a reader out there that reads all three tracks off a magnetic-stripe card, and gives you the raw characters encoded in it (or even the raw binary; since mag-stripes are encoded in bar-code like "bands" of on-off)?

To me either of these two implementations have the most promise for getting Bitcoin payments more easily handled for day-to-day transactions. Anyone else have thoughts on this?
2  Economy / Services / Creative services, at Midnight or other hours of the day on: September 12, 2012, 10:05:28 PM
I'm a creative professional who does freelance work in a variety of areas, and I'm willing to accept BitCoins as payment as well. I am well-skilled in Web Design, Web Development (Zend Certified PHP Engineer), Animation and Film work. I'd be happy to assist in logo design, web design planning and implementation, tuning and optimizing a website for performance (clearnet or deepnet; I can help improve the load time of either), development of web-based applications for desktop or mobile, plus 3D modeling and animation work for film or game use.

A full listing of creative services I can offer can be found on my portfolio site here. And of course, past works and other portfolio pieces are available on that site as well.

I quote all my work in USD, and use the Bitcoin charts 24-hour average for BTC value. Web and graphics work generally starts at $50/hr., so a simple, static website plus design usually runs $250-$500. Logo work around $100, depending on how clear a vision you have for it already. Drop me a line if there's a project I can help with!
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