Bitcoin Forum

Hi guys what's up, a newbie here.
I have a question in my mind about the paper wallet.
As I could understand, and to make a paper wallet offline, I need to download the html file of the BitAddress page and disconnect or disable any connection that I have in my computer then use a Linux liveCD, then open the html file that will generate private-public keys pair. After that I need transfer bitcoins from my wallet whereever they are to the public addresses on the paper.
Now, this in mind, the keys are generated while the computer is off-line, other person overseas may do the same procedure using the same html. There is no communication between the tasks of us and the addresses that produced on our computers are not introduced to the network neither to anywhere else.

Is there any probability that this html will generate one similar private-public pair for both of us?

How it comes that bitcoins can be transfered from a application wallet on a pc to a public address on the paper. The addresses in the paper are not introduced to the network. Then how can this transaction be verified and confirmed by the distributed network? How can the receiver wallet get its contents?


When I have these kind of questions I know that I am in the right way but at the same time I have this feeling that I missed something.

1) Private keys are generated randomly.  It is possible although incredibly improbable that two people would generate the same key.  If that happens you have an address collision and either person could spend the funds.  This isn't unique to paper wallets as all private keys are a random 256 bit number.  It also doesn't apply to just Bitcoin, it applies to all asyemtric encryption.  You could in theory in just one attempt generate a duplicate of the key used to sign google's SSL traffic and impersonate google.     The probability is so low that it is essentially 0%.

2) There is no such thing as "introduce an address to the network".  You can send funds to any valid address.  A paper wallet address is a valid address you send funds to it like you would sending funds to any other address.  The Bitcoin network has no idea what private keys or addresses have been generated it only knows which addresses have received funds in the past.

Thanks DeathAndTaxes,

Well,, that was good explanation. So, if someone sends bitcoins to an address on a paper, then I need to enter that address in a bitcoin wallet in order to get the bitcoins associated with that address. Right?
In the bitcoin wallet (The PCs wallet application)
I cannot enter a new address by myself, all I can do is to make a label and the address is generated randomly. How can I enter the address on paper in the PCs bitcoin wallet application?

Are you speaking about bitcoin-qt right? You can, but there is not a button in the interface for that, you have to use the console and type the right command, wich now i don't even remember

Thanks Gabi, I will search for that

To be clear to spend funds you need the private key not just the address (which is public knowledge).  So the command you are looking for is to import a private key.

The address is on paper and I want to enter that address in the Qt wallet in order to get its associated bitcoins. So, I am receiving not spending I guess.

Not sure how to do it in Bitcoin-Qt since I use Bitcoind but there are the API calls: https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list

This is what I use with bitcoind:

You can probably do something similar using the debug window of Bitcoin-Qt

Go in Help/Debug window/Console

Type:

Don't forget that if you send a transaction from that private key then the change will stay in your bitcoin-qt... not on your paper wallet!

Done  ;)

Yeah, it's very remotely possible that someone, somewhere might have the same private key as you. It's incredibly unlikely though, and it probably won't ever happen.