Bitcoin Forum

Bitcoins are not tied to a physical identity (be it a person or hardware) but instead to an electronic address.
Who owns a bitcoin address (or public key)?

If Bob knows the private key to access the coins at some address and Alice knows the private key to access the same coins, whose coins are they?

Are your coins my coins and my coins your coins?




How does one prove ownership of Bitcoin? If you and someone else both know the private key of some address, you can't prove ownership. Not with mathematics, for sure. How else?

Well it's unlikely it would be an issue for long as one of them would move the coins, if they weren't acting as one.

If such a trivial likelihood worries you, then do something that is dated and provable in a court - like copyright, post proof of it to yourself recorded delivery. Hold the earliest instance of a wallet, though perhaps equally remote that could be forged.

Better just not to share private keys. In the future shared accounts will likely be able to engage arbitrage that required both parties sign payments or random other scenarios.

true you can't prove ownership, but you can secure with password that no one else will be able to access and take the ownership of content.

A person owns bitcoins when they can prevent anyone else on the planet from manipulating those coins on the block chain.

If two people can simultaneously manipulate the same coins on the block chain, they are in a race to send them to an address under their sole control. They both own them, until they both don't.

Ok, lets make this more interesting. Forget about the private keys.

Who owns a specific public key, from a legal point of view?

Generally someone can prove "ownership" of Bitcoins by signing a short message with the private key used to control them.  If two people have the same private key then, as stated above, it would be a race to see who transfers them first to an address that they control by themselves.

I think there are more interesting cases:

Now an address can be set up to require M of N signatures to move the coins.  For example an address can be set up to require two out of three signatures in order to move the Bitcoins.  If three different people have the three different private keys and it takes two of them to move the coins, who "owns" the coins?

The public key is just a point on a curve with no usefullness or value without the private key.  Who owns the number 1234567?  Or better yet who owns the point on the unit circle at x=1, y=0?

I own the point (1, 0) on the unit circle. If I can move the contents of (1, 0) to another point, I'm 100% within my rights to do so, true?

Bitcoins cannot be "stolen".

"Owning" a public key makes no sense.  You can say you posses the private key that maps to that public key.  You can say by possessing the private key you "own" any BTC that have been sent to the public key.  You are correct, bitcoins themselves cannot be stolen, Bitcoin addresses and public keys cannot be stolen.  The only thing that matters, the only thing that can be stolen, is the private key.

True although proving that a private key was stolen could be hard. There is never 100% certainty.

Yes, this uncertainty is used all the time with the "We have been hacked, sorry, we don't have your BTC anymore" scenario that has played itself out over and over and over again in Bitcoinland.

There is no difference with cash.  I can own/posses the cash but how do I prove that it was stolen?