Key management #145

For now the entire PKI in bitcoin is closed for users. I propose make it more clear at least for JSON-RPC. It will be possible to create bitcoin paycards and such. All is required is to convert private (and maybe public, too) keys to base64 encoding and printing them to stdout and also implement creating private key in wallet.dat by importing such base64-encoded value. I guess public key may be easily calculated from private so when you export private you have no need to export public.

The purpose of this feature is to make possible creating deferred payments when you don't know (or don't want to know) whom to pay to. You give or leave the private key which has some amount of coins somewhere and recipient then withdraws money to his own wallet. With such functionality one can make a competition and the winner gets that key and receives money so you shouldn't worry about that. You send money to the new address, export its private key and place it to the page which is shown to the winner. And so on.

See the dumpprivkey and importprivkey rpc calls in this branch: https://github.com/sipa/bitcoin/tree/walletdump

Disclaimer: not ready for production use :)

Wow, glad you're working on it. Do you plan to release it for 0.3.21?

Well, I didn't want to close this issue, sorry. I have one idea to implement. Instead of importing private keys a transaction is created which sends money from supplied private key to any of user's address. That's how retrieving of bitcoin paycards may work. Party A generates a new address and sends money to it. Then it exports the private key, creates QR-code and prints it on pretty background. Then party A gives that piece of paper to party B. B makes a photo with its phone, webcam or any other device, recognizes QR-code and gets the private key. Then B executes the retrieval procedure (either via interface or via daemon) and fills in the form with two fields, the private key it got and the address it wants to receive money to. Bitcoin sends a regular transaction using this data, B gets the money and this private key become pretty unusable. I see no need to import the private key in the wallet, it's much safer to send all money from that address to yourself rather than just use it, because party A may get it back at any time. The shorter period between getting the key and retrieving the money the better.

Of course, if there are use cases of importing your own keys into wallet it may be implemented but for now it's easier to just send money from one wallet to another.

What you're suggesting is partially implemented already, see http://www.bitcoin.org/smf/index.php?topic=4555.0 and http://bitcoin.modernjob.info/print.html

What I'm working on now is a export/import function for entire wallets (or selected parts thereof). I can imagine some use cases: backups, shared wallets (though that's still asking murphy to visit you), debugging (quite useful to be able to see the contents of your wallet, and per-key available funds), recovery (exporting and importing a corrupt wallet file will often get you your funds back), ...

Maybe later it can be combined with jgarzic's scratchoff patch to have a "send funds to new address, and export that" and a "send all available funds in imported file to own address" mode as well.

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