A "real" Bitcoin - page 2. | Bitcointalksearch.org

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Quote from: TiagoTiago on February 20, 2011, 11:59:21 AM

I can see a future where "paper" money will contain flexible electronics and display tecnology, a single note will be capable of holding any amount of bitcoins you transfer to it (it will be a physical standalone wallet), and will change it's appearance to reflect it's contents; you will be able to exchange notes without using any network, or even electricity, like how you exchange paper money nowadays, but with a device (any one of the many types that will be avaible) you will have the ability to redistribute the Bitcoins between notes as well between notes and other wallet storage means. (An empty note would only have a very small value simply for the benefits it has for exchanging Bitcoings instantly and without needing any connection or energy once charged, they would be made in great numbers, so many that people will feel more confortable throwing away an empty one than people nowadays feel about leafs falling from trees)

If I have a wallet with bitcoins I can put that file on all my computers simultaneously. When I spend them they are gone from all computers. I can do the same with the suggested bills. If there is a way to put them on one then I can put them on many. The network is required for preventing double spending. You either have to trust the person you are trading with or you have to be on the network.

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Firstbits.com/1fg4i :)

I can see a future where "paper" money will contain flexible electronics and display tecnology, a single note will be capable of holding any amount of bitcoins you transfer to it (it will be a physical standalone wallet), and will change it's appearance to reflect it's contents; you will be able to exchange notes without using any network, or even electricity, like how you exchange paper money nowadays, but with a device (any one of the many types that will be avaible) you will have the ability to redistribute the Bitcoins between notes as well between notes and other wallet storage means. (An empty note would only have a very small value simply for the benefits it has for exchanging Bitcoings instantly and without needing any connection or energy once charged, they would be made in great numbers, so many that people will feel more confortable throwing away an empty one than people nowadays feel about leafs falling from trees)

em3rgentOrdr

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youtube.com/ericfontainejazz now accepts bitcoin

Quote from: casascius on January 11, 2011, 10:26:49 AM

Quote from: em3rgentOrdr on January 11, 2011, 01:35:31 AM

Quote from: casascius on January 09, 2011, 12:06:09 AM

I assert that a smart card is a physical object that can securely store a bitcoin.

A smart card is an integrated circuit that, among other things, can store a private key and sign things with it without divulging the private key. A smart card can also enforce pre-programmed constraints by itself. Many smart cards can generate public/private key pairs on-chip, and encrypt/decrypt data streams in real time.

However, is there a way that you can verify the bitcoin wallet that you embed inside this smart card chip has NO OTHER COPIES? Potentially, couldn't the manufacturer or distributor of these bitcoin smart cards keep a backup of the wallet at their company headquarters when they first create the bitcoin smart card? I guess maybe you can't trust a pre-loaded bitcoin smart card, and instead can only trust bitcoin smartcards that you generate a new address inside it yourself which gets sent a bitcoin.

Bitcoin has the ability to encumber coins with multiple keys and specify that "all" of them are needed to spend the coins. It's not visible in the user interface, but it exists in the protocol. A viable "tangible" bitcoin would be backed by coins that are secured by at least two keys. One of them would be put there by the manufacturer, the other would would be field-changeable by any user in possession of the card. If the manufacturer of the card does not have ALL the keys encumbering the card, he cannot steal the coins.

This would also guard against copies. The moment any user rekeyed that second key, all other copies would be void the moment the rekeying hit the block chain.

I like that idea of using multiple keys...

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Quote from: em3rgentOrdr on January 11, 2011, 01:35:31 AM

Quote from: casascius on January 09, 2011, 12:06:09 AM

I assert that a smart card is a physical object that can securely store a bitcoin.

A smart card is an integrated circuit that, among other things, can store a private key and sign things with it without divulging the private key. A smart card can also enforce pre-programmed constraints by itself. Many smart cards can generate public/private key pairs on-chip, and encrypt/decrypt data streams in real time.

However, is there a way that you can verify the bitcoin wallet that you embed inside this smart card chip has NO OTHER COPIES? Potentially, couldn't the manufacturer or distributor of these bitcoin smart cards keep a backup of the wallet at their company headquarters when they first create the bitcoin smart card? I guess maybe you can't trust a pre-loaded bitcoin smart card, and instead can only trust bitcoin smartcards that you generate a new address inside it yourself which gets sent a bitcoin.

Bitcoin has the ability to encumber coins with multiple keys and specify that "all" of them are needed to spend the coins. It's not visible in the user interface, but it exists in the protocol. A viable "tangible" bitcoin would be backed by coins that are secured by at least two keys. One of them would be put there by the manufacturer, the other would would be field-changeable by any user in possession of the card. If the manufacturer of the card does not have ALL the keys encumbering the card, he cannot steal the coins.

This would also guard against copies. The moment any user rekeyed that second key, all other copies would be void the moment the rekeying hit the block chain.

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Quote from: Pegasus-Rider on January 09, 2011, 05:34:43 PM

For minting we may refer to Wirtland project experience and perhaps even propose bitcoin as their currency on this occasion.
How does it sound?

Wirtland would be glad to collaborate, I guess. (By the way, our next physical coin will be with Julian Assange portrait, see http://www.tiny.lu/o27px!) But I have to agree that a smart card, such as an anonymous VISA, would be much better for practical use. In fact, Wirtland has been discussing this for a long time. Wirtland issues plastic IDs, and wants to have them serve for payments - by inserting chip, magnetic band or other technology.

em3rgentOrdr

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youtube.com/ericfontainejazz now accepts bitcoin

This whole discussion reminds me of the "Printing Bitcoins : Could it Work?" discussion.

Quote from: Mike Hearn on January 01, 2011, 06:48:37 AM

It'd be cool to come up with a coin design that's RepRappable. It'd fit well with the decentralized philosophy of BitCoin :-)

http://reprap.org/

For making it an actual coin that's useful for transactions, you could embed an NFC chip into it. The tag chips cost about a dollar, I think, and can store small amounts of arbitrary data that can then be read by near field radio. It'd probably be possible to fit a keypair into it.

I like that idea. Where can I buy a NFC chip today for a dollar?

Quote from: grondilu on January 08, 2011, 10:31:46 PM

IMO, you're taking this way too seriously guys.

A physical bitcoin is cool, but it's nothing but symbolic. There is obviously no way to have any physical object store a bitcoin. Otherwise we wouldn't need bitcoin in the first place. A physical object can be counterfaited, and if you plan on putting ECDSA keys in it, it can be copied. And you still have the double spending problem. And I'm sure there are many other reason why a physical bitcoin can be nothing but some kind of a marketing toy or something alike.

Still, I'd like to have one. Especially if it's solid gold.

I like the idea of backing gold with something of real value, like bitcoin. Heck, fundamentally, gold is currently "backed by nothing!" (deliberate scare quotes) Tongue

Quote from: casascius on January 09, 2011, 12:06:09 AM

I assert that a smart card is a physical object that can securely store a bitcoin.

A smart card is an integrated circuit that, among other things, can store a private key and sign things with it without divulging the private key. A smart card can also enforce pre-programmed constraints by itself. Many smart cards can generate public/private key pairs on-chip, and encrypt/decrypt data streams in real time.

EXACTLY! Excellent idea. Just embed this bitcoin smart card chip with NFC inside of a plastic rep-rap or makerbot plastic 'coin' and you have a "real" bitcoin!

However, is there a way that you can verify the bitcoin wallet that you embed inside this smart card chip has NO OTHER COPIES? Potentially, couldn't the manufacturer or distributor of these bitcoin smart cards keep a backup of the wallet at their company headquarters when they first create the bitcoin smart card? I guess maybe you can't trust a pre-loaded bitcoin smart card, and instead can only trust bitcoin smartcards that you generate a new address inside it yourself which gets sent a bitcoin.

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Quote from: ribuck on January 10, 2011, 06:03:11 AM

Fractional reserve banking, in other words. I'm not criticizing though. It's inevitable, and it's harmless provided the level of backing behind the "pegging" is honestly disclosed.

I suppose you could call it that. I envision an issuer as making the market for the currency, rather than accepting deposits and issuing bearer certificates. Perhaps its just semantics, but in making the market for a pegged currency for an honest, razor thin spread, an issuer would demonstrate a consistent commitment to maintain its trade value at face value.

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Quote from: Vinnie on January 09, 2011, 05:37:05 PM

If and when BTC becomes more widely accepted, I'd consider starting a physical currency that is pegged to bitcoins.

Fractional reserve banking, in other words. I'm not criticizing though. It's inevitable, and it's harmless provided the level of backing behind the "pegging" is honestly disclosed.

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Quote from: Pegasus-Rider on January 09, 2011, 05:48:59 PM

Quote

If and when BTC becomes more widely accepted

It might be this very initiative that will help to popularise Bitcoin - you know, a /. post about it, news site articles and so on.

True. What do you think; paper bills or coins?

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Quote

If and when BTC becomes more widely accepted

It might be this very initiative that will help to popularise Bitcoin - you know, a /. post about it, news site articles and so on.

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Quote from: grondilu on January 09, 2011, 02:40:25 AM

Am I missing something or what ? If you give the smartcard, the only way for the receiver to check that it realy has some value is to proceed to a transfer. Then the card doesn't have any value anymore. So what's the point of keeping it ?

A physical-world digital store of money has many uses. Anonymous, reloadable VISA debit cards are quite popular, for example. A card would be nothing more than an anonymous bitcoin wallet.

Currently bitcoins are as portable as your computer... but they could be more portable with a smartcard.

Simply handing someone a card is a useful way to move money.

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If and when BTC becomes more widely accepted, I'd consider starting a physical currency that is pegged to bitcoins.

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I would like to see a traditional coin representing BTC, and I see it as follows:
It would be made of a valuable metal or alloy (Germanium-Titanium sounds extremely attractive, particularly because of its bit-significance), with Bitcoin symbols and guarantee to exchange such tokens for bitcoins, effectively making these representative money with a meaningful value of their own.
For minting we may refer to Wirtland project experience and perhaps even propose bitcoin as their currency on this occasion.
How does it sound?

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Quote from: grondilu on January 09, 2011, 03:16:10 PM

It seems to be quite complicated but I guess it's possible.

I don't think it would harm the bitcoin network anyway, so go for it.

Here's some context:

http://img810.imageshack.us/i/photoph.jpg/

These credit card machines are nothing more than simple desktop computers with a POSIX-like proprietary OS that can be written to in C / C++. This is a "proof of concept" video poker application I wrote for the VeriFone Vx series credit card machines.

Each of these machines has a smart card reader, and the API allows the sending and receiving of arbitrary commands to the smart card... a smart card with custom application can handle these however it has been programmed.

edited to add: the real obstacle is that it would be necessary for Bitcoin to allow bitcoins to be encumbered by a second private key. Otherwise all kinds of attacks are trivial. Someone suggested this was already possible - I'm afraid I don't understand the workings of the Bitcoin protocol well enough at this point to say whether or not that was so.

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Quote from: casascius on January 09, 2011, 03:10:10 PM

If the smart card had a custom application that simply proved that it contained the private key associated with some real Bitcoins out there, the value could be checked simply by confirming that the corresponding Bitcoin address had a balance.

If the Bitcoin system allowed bitcoins to be encumbered by TWO private keys instead of one, and the second one were settable by any user in possession of the card (a change would be announced to the blockchain so it would be enforced by all nodes), it would eliminate the risk that someone who secretly acquired the private key within the card (e.g. the manufacturer) could spend the coins after he had given away the card.

It seems to be quite complicated but I guess it's possible.

I don't think it would harm the bitcoin network anyway, so go for it.

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Quote from: grondilu on January 09, 2011, 02:40:25 AM

Quote from: casascius on January 09, 2011, 01:48:18 AM

Why not? A smart card can be given away just like any other tangible object.

Am I missing something or what ? If you give the smartcard, the only way for the receiver to check that it realy has some value is to proceed to a transfer. Then the card doesn't have any value anymore. So what's the point of keeping it ?

If the smart card had a custom application that simply proved that it contained the private key associated with some real Bitcoins out there, the value could be checked simply by confirming that the corresponding Bitcoin address had a balance.

If the Bitcoin system allowed bitcoins to be encumbered by TWO private keys instead of one, and the second one were settable by any user in possession of the card (a change would be announced to the blockchain so it would be enforced by all nodes), it would eliminate the risk that someone who secretly acquired the private key within the card (e.g. the manufacturer) could spend the coins after he had given away the card.

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Quote from: casascius on January 09, 2011, 01:48:18 AM

Why not? A smart card can be given away just like any other tangible object.

Am I missing something or what ? If you give the smartcard, the only way for the receiver to check that it realy has some value is to proceed to a transfer. Then the card doesn't have any value anymore. So what's the point of keeping it ?

casascius

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Quote from: grondilu on January 09, 2011, 12:18:20 AM

Yeah but to pay with a smartcard, you don't give the smartcard ! It's a completely dofferent purpose than a monetary token.

Why not? A smart card can be given away just like any other tangible object.

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Quote from: casascius on January 09, 2011, 12:06:09 AM

I assert that a smart card is a physical object that can securely store a bitcoin.

A smart card is an integrated circuit that, among other things, can store a private key and sign things with it without divulging the private key. A smart card can also enforce pre-programmed constraints by itself. Many smart cards can generate public/private key pairs on-chip, and encrypt/decrypt data streams in real time.

Yeah but to pay with a smartcard, you don't give the smartcard ! It's a completely dofferent purpose than a monetary token.

casascius

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Quote from: grondilu on January 08, 2011, 10:31:46 PM

IMO, you're taking this way too seriously guys.

A physical bitcoin is cool, but it's nothing but symbolic. There is obviously no way to have any physical object store a bitcoin. Otherwise we wouldn't need bitcoin in the first place. A physical object can be counterfaited, and if you plan on putting ECDSA keys in it, it can be copied. And you still have the double spending problem. And I'm sure there are many other reason why a physical bitcoin can be nothing but some kind of a marketing toy or something alike.

Still, I'd like to have one. Especially if it's solid gold.

I assert that a smart card is a physical object that can securely store a bitcoin.

A smart card is an integrated circuit that, among other things, can store a private key and sign things with it without divulging the private key. A smart card can also enforce pre-programmed constraints by itself. Many smart cards can generate public/private key pairs on-chip, and encrypt/decrypt data streams in real time.

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