The bitcoin app for android can initiate transactions with NFC or QR codes.
https://code.google.com/p/bitcoin-wallet/
http://f-droid.org/repository/browse/?fdid=de.schildbach.wallet&fdpage=3
https://play.google.com/store/apps/details?id=de.schildbach.wallet
You have to have internet available on both phones.
Any other way of doing it, you're going to have to rely on a central authority to issue the money, and/or track spending, and/or prevent double-spending, and/or prevent counterfeiting.
It's been done. A number of "local currencies" exist. They usually issue cash in the form of paper money.
https://en.wikipedia.org/wiki/Local_currency
Now, what *I*'d like to see is a way of computer-assisting the bartering process.
Someone puts up a thing that's like "I will cut someone's hair but I want a new blender", and then someone else puts up "I will give someone my blender but I want a home-cooked dinner" and someone else is like "I will make someone a home-cooked dinner but I want my hair cut" and then the computer can get all these people in contact with each other. With a website, and with a lot of people using it, you could compute long chains of barter that wouldn't be obvious to people.
Let's cut out the middleman (money) and exchange value directly! by inserting a new middleman (this website)!
How does the protocol work? I'm imagining a doohickey that stores transactions on it, and has the current value of the doohickey.Any other way of doing it, you're going to have to rely on a central
authority to issue the money, and/or track spending, and/or prevent
double-spending, and/or prevent counterfeiting.
I strongly disagree. Cryptography and a meeting in person should be enough to ensure
authenticity.
I can sign a transaction and send it to you: "I hereby bequeath $20 unto you". You see my signature, and you see that my pubkey is signed by a trusted authority, and so you accept my $20. If you try to give that $20 to somebody else, they'll see that it has your signature, your signature is valid, and it has my signature, and my signature is valid, so they accept it.
But what if I "forget" to write down that I gave that money to you, and then I give it to somebody else? Then one day, bob tries to give carol $20 and carol says "you can't give me that particular $20. I already have that $20!" and then I, in the shadows, go "muahahahaha".
Solutions to this problem that I know of are:
* Have physical objects that are gone when you spend them (gold, cash).
In the case of cash, a central authority has to prevent counterfeiting.
* Have a central authority verify each transaction, and disallow
transactions where the spender doesn't have the money they claim to.
Bob won't accept a transaction from Alice until the authority verifies
it. Requires a connection to the internet and a central authority.
* The bitcoin block chain, which implements the central authority in a
peer-to-peer fashion. Requires a connection to the internet.
Do you have another plan?
Just pointing out that if a concept or a thing is difficult to summarize in text in an email, how is it going to be any easier to summarize on a Wiki page?
Now, what *I*'d like to see is a way of computer-assisting the barteringYou mean http://ripple-project.org/ ?
process.
Ripple is a step toward that.
I will check that out soon, thanks.
I believe Ripple avoids the issue of duplicating currency, because Ripple is not a currency--it's an IOU. If I understand it correctly, Ripple "payments" (cancellation of IOUs) can only be made along chains of trust relationships. The idea is that small-world network effects would allow you to have at least one trust-chain to any random merchant on the web.Now, what *I*'d like to see is a way of computer-assisting the barteringYou mean http://ripple-project.org/ ?
process.
Ripple is a step toward that.
I will check that out soon, thanks.
The main issue I see with decentralized Ripple is that IOUs in different social networks can have different real-world values. I guess the current approach is to set up IOU exchanges, but how do you determine the relative values of IOU units distributed across the net? It might be a lot simpler to just tie IOUs to a real currency such as the US$.
Keeping authentication as only F2F will mean that whatever system you make will always stay very small and static.