[Blog Post] Our Discovery in Vienna – The Bitcoin Card

[Piper67]

And another thing... if this device also acted like a Yubikey, then it could replace the Bitinstant, MtGox and other yubikeys. So they could put a nice looking logo on it and sell it as a yubikey/wallet. I'd definitely get one for 10 to 20 USD then.

[cbeast]

These might be ideal "Green Address" cards which can be issued by a government, tracked, and controlled. That is not necessarily a bad thing.

[Elwar]

You mention that you will see an alias of the local users on the network and be able to scroll through and pay the right one.


Imagine I am at Joe's Pizza Place and he has his alias set up as JoesPizzaPlace.


Punk ass kid at the restaurant changes his alias to JoesPizzaPIace, or Joe'sPizzaPlace or J0ESPIZZAPLACE.

What is to prevent people from sending BTC to the wrong alias?

[mccorvic]

You mention that you will see an alias of the local users on the network and be able to scroll through and pay the right one.


Imagine I am at Joe's Pizza Place and he has his alias set up as JoesPizzaPlace.


Punk ass kid at the restaurant changes his alias to JoesPizzaPIace, or Joe'sPizzaPlace or J0ESPIZZAPLACE.

What is to prevent people from sending BTC to the wrong alias?

A big signs at Joe's saying "DON'T PAY THAT DUDE WITH THE FAKE NAME"?

EDIT: Upon rereading the aforementioned bullet: it says that each device has a unique name, not that everyone gets to choose their own name.  If it does turn out that users get to choose their own name, maybe there will be an option that you can still check the bitcoin address in the event that two name appear similiar.

[apetersson]

You mention that you will see an alias of the local users on the network and be able to scroll through and pay the right one.


Imagine I am at Joe's Pizza Place and he has his alias set up as JoesPizzaPlace.


Punk ass kid at the restaurant changes his alias to JoesPizzaPIace, or Joe'sPizzaPlace or J0ESPIZZAPLACE.

What is to prevent people from sending BTC to the wrong alias?

that is actually a good question.

[fatigue]

These might be ideal "Green Address" cards which can be issued by a government, tracked, and controlled. That is not necessarily a bad thing.

The hell.... One of the main points of Bitcoin is that its not controlled by any governing system....

[Serith]

These might be ideal "Green Address" cards which can be issued by a government, tracked, and controlled. That is not necessarily a bad thing.

The hell.... One of the main points of Bitcoin is that its not controlled by any governing system....

There is a better idea then Green Address about how to accept 0-conf txn: https://bitcointalk.org/index.php?topic=88442.0, but some centralization from major pools still required though.

[Foxpup]

The devices hold private keys on them. These can be backed up via the company’s website, but it is not necessary to ever interface with the company in order to use the device.

If you can't back it up yourself, it's a weakness. It should be able to display the private keys or a seed on the screen so you could take a picture of it.

+1

[Daily Anarchist]

Cuuurious. I like the local nature of it. But I'm left wondering - what does it do, other than generate its own power, that I couldn't do with my phone?

That's a genuwine question, because I do like the sound of the device. To answer myself a little, I like that it makes sending btc very easy, i.e. hides the idea of an "address" and replaces it with a device. Could a smartphone do something similar via Bluetooth/Google Maps/etc though?

Well, it's cheap which could aid user penetration into areas/demographics that cannot afford smart phones.  That's just off the top of my head.

I'm curious how they plan on reaching any sort of "critical mass" of users to make the thing work. "Here, buy this thing and hold on to it! It might work...eventually" doesn't sound like a promising business plan.

To me that is a plus because I can pay once for it instead of spending gobs of money every month on a smartphone contract. This would be huge for the developing world.

[Azrael_PT]

WANT. NOW. The future awaits....

Edit: is there any dev site for this currently?

http://www.bitcoincard.org/
http://vimeo.com/40711689

[DeepBit]

The devices hold private keys on them. These can be backed up via the company’s website, but it is not necessary to ever interface with the company in order to use the device.

If you can't back it up yourself, it's a weakness. It should be able to display the private keys or a seed on the screen so you could take a picture of it.

Yes, it's a must. At least.
Of course interfacing with PC would be even better.

Bitcoin enthusiasts may not like backup centralization, BTW.

[apetersson]

These can be backed up via the company’s website

I think this was never discussed - at least not in the explanations i was given. How the private keys are handled is still open to discussion. but a "cloud" backup was not suggested.

Bitcoin enthusiasts may not like backup centralization, BTW.

exactly.

[check_status]

How do you prevent someone from polling all nearby wallets for balances? Like if you walk into a casino or some futuristic/hacker/mugger?

[MoonShadow]

How do you prevent someone from polling all nearby wallets for balances? Like if you walk into a casino or some futuristic/hacker/mugger?

I'm not sure that I understand the question.  You can't poll a bitcoin client for it's balance.  None that I know of even allow that as an optional feature with user approval.  The only thing that you could do is capture a card's bitcoin address during an over-the-air transaction, and then scan the blockchain.  But what good would it do you?  Help you find a mark to mug?  A couple of these events and users will be demanding an off (or radio silence) switch and a pin code to use the device at all.  Actually, neither is a bad idea, per se.  If someone mugs you for your wallet, you give it up and are just thankful you didn't get hurt.  If you have a backed up bitcoincard with a pin locked wallet, all they get is a worthless piece of plastic and a small solar cell.  If you didn't back it up, you don't recover your money, but neither do they.  Even guessing a four or five digit pin over and over again is going to take quite a bit of effort and time, and there is no way a mugger could know that you didn't have a backup and will move those funds in the next 1o minutes.

[caveden]

The devices hold private keys on them. These can be backed up via the company’s website, but it is not necessary to ever interface with the company in order to use the device.

If you can't back it up yourself, it's a weakness. It should be able to display the private keys or a seed on the screen so you could take a picture of it.

I also wonder the same thing. Why is their server involvement necessary for the backup process? Can anybody tell?

If the server holds the btc private keys, that's awful. But that would go against what's said in the same post:

An overarching design principle of the devices is to eliminate the requirement of trust in any single party, even in the manufacturer. Details of how this is accomplished are not fully fleshed out yet, but include ideas like having the devices only create their key pair after they are in the consumer’s hands (so not even the manufacturer would know it).

So, why is the server necessary? Does the server hold a specific key in which the device trust, and the device would both require the signing of challenge by that key as well as physical intervention (pressing buttons) before releasing the private key for backup?
Although that would considerably decrease the danger of the server having its key hacked, as the key alone wouldn't do much, I just don't see the point in such architecture...

Btw, will the device be able to use deterministic wallets?

[apetersson]

I also wonder the same thing. Why is their server involvement necessary for the backup process? Can anybody tell?
If the server holds the btc private keys, that's awful. But that would go against what's said in the same post:

An overarching design principle of the devices is to eliminate the requirement of trust in any single party, even in the manufacturer. Details of how this is accomplished are not fully fleshed out yet, but include ideas like having the devices only create their key pair after they are in the consumer’s hands (so not even the manufacturer would know it).

So, why is the server necessary?

It isn't. I don't know where the information with the servers came from, but afaik, its not true. The details of the way the bitcoincard will be handling private keys is not finalized but storing them on central servers was never an option.

[caveden]

Thanks apetersson for the clarification.

This looks very promising.