Sending bitcoins to an un-owned, well-formed wallet

Question

This is a follow-up question to: What happens if I mistype the address when making a payment?.

Scenario:

1. You're trying to send bitcoins to an address.
2. You type in the wrong address, but the address (as unlikely as it may be) is well-formed.

What Happens?

1. The wallet belongs to someone and you've just sent him money. (Can one contact this person and ask for it to be returned?) The key phrase is "can one contact" not "can you force him to give it back."
2. The wallet (as seen in the quote below) is unowned and the bitcoins are lost!?!

Bitcoin addresses contain a built-in check code, so it's generally not possible to send Bitcoins to a mistyped address. However, if the address is well-formed but no one owns it (or the owner lost their wallet.dat), any coins sent to that address will be lost forever. https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses

Is it lost? Or, if and when, this wallet is created are the "missing" bitcoins attached to it?

Answer 1

Most transactions create an Unspent Transaction Output (UTXO) which can only be spent by the owner of the corresponding recipient address. Any "well-formed address" can receive such a transaction, whether it has been used before or not.

Should somebody own the address, they might try to send the money back to the original sending address, however, it is not certain that the sender owns the address that he sent from. It would probably be better to try to contact the other via one of the numerous bitcoin forums: Since addresses are unique, they make great search terms.

Should nobody own the address, the coins are likely to be "lost", in the sense that they would be spendable, but nobody will ever generate the corresponding private key.

Also see

• What would happen if you send bitcoins to a non-existent Bitcoin address?
• Is it possible to brute force bitcoin address creation in order to steal money?.

Answer 2

The wallet belongs to someone and you've just sent him money. (Can one contact this person and ask for it to be returned?) The key phrase is "can one contact" not "can you force him to give it back."

Not unless the owner of that address has publicly stated that she owns that address (perhaps on her blog or on a forum? Try googling).

The wallet (as seen in the quote below) is unowned and is lost!?!

If the receiving address is valid and has not been used (you can find out from any online blockchain explorer), then it is highly likely that you've sent your coins to an address that nobody can claim (yet). In fact, it is almost certain that nobody will ever be able to generate a private key for that address. Therefore those coins will most likely be stuck in that address forever.

However, if the receiving address has been used, then there's a possibility of you getting in touch with that person and hope for her kindness. The problem is that there's no facility in Bitcoin for getting to know the identity behind a bitcoin address unless they explicitly provide this information.