As I have seen, there already are some projects regarding wallet on smartphone (at least on the android devices), and we are considering this, or at least supporting something like this. But as smartphone systems are complex, there is a lot of room for security issues, and we want to make something that will be secure enough to prevent at least remote hacking. Nobody will bother to hack for 10$, but if you can replicate the hypothetic issue on a number of phones, the profit could be large. With smart card you need physical presence to hack them (Or so I believe)

Thanks for the suggestion though!

There are two different usage scenarios I was talking about here:

The one we are concentrating on is
1.  A Bitcoin smart card that would contain a separate wallet you could "fill-up" and go shopping outside, here you would back up your wallet by making a copy of keys when initializing the smart card

The one i guess you are referring to, and which was just an after-tought to the first one
2. A Bitcoin card that holds your "main" wallet key and you keep at home in your smart card reader, that authorizes transactions by signing them (after you enter the pin), therefore mitigating the risk, i was talking about backing up the keys of this card on a safe location. This would prefent malware, keylogers etc, from getting your keys.


As for the device proposition, we are actively talking about such device, but we want to start cost efficient and with less development at first, and concentrate on a smart card. The hardware device would come later, or if we have enough resources (manpower and expertize) we could do it in parallel.

Anyways, thanks for your input on this!

We have considered this approach also,in one scenario, you would have:
1.(at home) a secure smart card reader with display and keypad (something like this http://www.smartcardfocus.com/shop/ilp/id~312/ACR83/p/index.shtml)
2. your "main" wallet smart card (this smart card wouldn't be used for small transactions when you are out shopping).

Whenever the bitcoin client wants to send bitcoins, it would send the card request to sign a certain amount of bitcoins, the amount would be shown on the the display, and you would enter your pin to confirm the request. This would secure your transactions from keyloggers and malware as long as the card reader is not compromised. Of course there would need to have a backup of your wallet.dat so that in case you lose your smart card (unlikely for a "main" wallet smart card) you don't lose the coins. This backup would of course be on a media not stored in your network-connected pc (usb in safe is a safe bet )

You can see the more links on http://bitcoincard.wikispot.org/Front_Page (Oh, and a perfect opportunity to ask if someone is willing to administer the wiki?)

@bitcoindude & acesun
Thanks for the support!

@enmaku

I agree with you that this solution would be the most cost effective and ubiquitous, but we haven't really considered mag-stripe cards yet, and the reason is (other than I know very little about them:) ) that we want to provide a certain level of security. With mag-stripes the problem is that they could be cloned, and then easily brute-forced to reveal the private key. With a normal card in this situation you could call your bank and declare the card invalid before most of the damage is done, but with bitcoins that option doesn't exist. Of course I strongly support the development of mag-stripe bitcoin cards if there are people willing to use it, it's just that I would like for us to focus first on smartcard based cards because they provide a higher level of security. My suggestion is to prioritize development in this order:

1. Smartcard Bitcoin card
2. Custom hardware with keypad and display Bitcoin card
3. Mag-Stripe Bitcoin card

If we can gather enough people and resources to develop all of three of these options in parallel, excellent!

Again, I must say, that I'm not an expert in this area, and if my assumptions are wrong, please correct me, I would also like to receive continued input from the community during the development of the project. The project is still in it's early beginnings, but already people are starting to participate, and I am really happy about that. 

Hey everyone,

Yesterday a few people from #bitcoin and myself decided to start an open source project with the aim of designing/producing a physical Bitcoin card, not unlike standard credit cards

The card would contain a separate wallet, which you could recharge from your computer.
Currently there are several proposals on the card concept, and the two most practical are :

1. Smartcard with custom software to support BitCoins
2. Custom hardware dongle/card with display and keypad for increased security

The other part of the project is the desktop-side software which would take care of backing up the cards wallet, and general management related to the BitCoinCard

Both approaches have their pros and cons

On the note that that the BitCoin is not ready for this type of usage, I agree, but it doesn't prevent us from starting on time, and have a solution when it's ready

You can follow and join the discussion here: http://groups.google.com/group/bitcoincard

Wiki (which is currenly unorganized and mostly empty): http://bitcoincard.wikispot.org/Front_Page
GitHub repository (also empty): https://github.com/ionspin/BitCoinCard
The project is just beginning, and any input and support will be appreciated!


Note to mods, as this is my first post, I can only post in the newbies section, so please move the topic to the appropriate session. Thanks!