Is it possible to send BTC to an address that doesn't exist?

[knight22]

if I made a mistake in a BTC address, where my BTC will go?

[paraipan]

if I made a mistake in a BTC address, where my BTC will go?

A picture is worth more than a thousand words, they say...

[knight22]

 
pretty clear answer!

[Qoheleth]

There's a certain number of parity bits in Bitcoin addresses, so if you're only one letter off, a sane client should be able to detect that and warn you.

But if the parity bits check out... yeah, those coins are basically destroyed.

[DeathAndTaxes]

There is a checksum in the Bitcoin address.  The network will reject funds sent to INVALID addresses (not to be confused with "VALID but not the one I intended to send it to" addresses).

The odds of accidentally mistyping an address and it still be valid is roughly 1 in 4 billion.  So while the risk exists it is not really something to worry about.  It is more common that funds are lost because they are accidentally sent to the wrong (properly typed and valid but not intended) address.

[hazek]

if I made a mistake in a BTC address, where my BTC will go?

Don't think of them as existing or not existing, think of them as being valid or invalid.

And since the Satoshi client(and most if not all others) allows you to only make a transaction using a valid Bitcoin address, you couldn't have sent it to an invalid one. The only question remaining now is whether you have the private key corresponding to the valid address you sent your bitcoins to, and if you don't does someone else.. and if no one does the bitcoins are lost just as if you deleted your wallet file with all your other private keys.

[nimda]

Here's an address:
1BitcoinEaterAddressDontSendf59kuE
While the checksum is valid, it's pretty safe to say that nobody owns the private key for 2 reasons:
-The probability of generating a case-sensitive vanity address that long is incredibly low
-All of its inputs are unspent

[Sukrim]

There are 2 choices:

First choice: Is the address valid?
Bitcoin adresses (similar to credit card numbers for example) have certain criteria they have to fulfill to be a valid address. Most clients will stop you from sending anything to an invalid address and no coins will ever be actually sent (= transaction included in a block) to an invalid address.

Second choice: Does someone actually own the private key to a valid address?
See the example with the "1BitcoinEater..." address above: it's a valid address, but very very VERY likely nobody will ever find a private key to be able to actually spend any coins sent there. You can send funds to any valid address you can think of (and there are many!), but only with a corresponding private key people will be able to actually spend these funds. Think of it like a bank deposit box, where you can (through a hole or something) deposit envelopes filled with cash - but only if somebody actually has the key to the box, he'll be able to get the money out and spend it. Bitcoin has a LOT of these boxes - so many, that you can simply generate your own key and claim the one box that fits as yours. It's practically impossible that anyone else would choose the same key, as there are so many boxes (addresses) out there.

[mav]

See the example with the "1BitcoinEater..." address above: it's a valid address

Nope

Code:

bitcoind validateaddress 1BitcoinEaterAddressDontSendf59kuE

Code:

{
    "isvalid" : false
}

There's a checksum. Just cause it starts with 1 and is the 'right' length doesn't mean it's always valid.

Edit: I checked this forgetting that I was on testnet. haha nevermind me.... 

[unclemantis]

See the example with the "1BitcoinEater..." address above: it's a valid address

Nope

Code:

bitcoind validateaddress 1BitcoinEaterAddressDontSendf59kuE

Code:

{
    "isvalid" : false
}

There's a checksum. Just cause it starts with 1 and is the 'right' length doesn't mean it's always valid.

Unless you are typing an address by hand this is not likely. Even if you make a typo or a few and they end up correcting themselves and making a valid key, the chances are pretty slim.

[Nyhm]

Here's a mathematically, cryptographically proven process for recovering bitcoins sent to a valid but otherwise unintended address. A vanity address generator can be used to reverse-engineer the private key from the (public) address. Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for, at which point you have the private key to reclaim your funds. Of course, you may need to wait several thousand years to find a match. The upside is that, by that time, Bitcoin will surely be the dominant currency in the local extra-solar economy, and your small sum today will certainly be worth quite a bit more due to deflation (only 21 million bitcoins being spread over a multi-planetary market).

Hope this helps.

[DeathAndTaxes]

Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for, at which point you have the private key to reclaim your funds. Of course, you may need to wait several thousand years to find a match. there isn't sufficient energy in our sun to power a perfect (in the theoretical physics sense) computer that could attempt even a trillionth of 1% of possible addresses before our sun burned out. ...

FYPFY.  Baring a cryptographic flaw being discovered in ECDSA there is no possibility of ever recovering lost bitcoins.  Well not until man is able to harness power sources many hundreds of magnitudes more powerful than our star.

[Nyhm]

Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for, at which point you have the private key to reclaim your funds. Of course, you may need to wait several thousand years to find a match. there isn't sufficient energy in our sun to power a perfect (in the theoretical physics sense) computer that could attempt even a trillionth of 1% of possible addresses before our sun burned out. ...

FYPFY.  Baring a cryptographic flaw being discovered in ECDSA there is no possibility of ever recovering lost bitcoins.  Well not until man is able to harness power sources many hundreds of magnitudes more powerful than our star.

Awesome!

[unclemantis]

Well, Since it's apparently possible to send coins to an address that doesnt exsist, What if it gets created later down the road? Would it "pickup" the funds since the blockchain says "100btc to XYZ was sent 5years ago, OH LOOK! Theres XYZ!, Here you go XYZ!"

In a single word YES

[caveden]

Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for, at which point you have the private key to reclaim your funds. Of course, you may need to wait several thousand years to find a match. there isn't sufficient energy in our sun to power a perfect (in the theoretical physics sense) computer that could attempt even a trillionth of 1% of possible addresses before our sun burned out. ...

FYPFY.  Baring a cryptographic flaw being discovered in ECDSA there is no possibility of ever recovering lost bitcoins.  Well not until man is able to harness power sources many hundreds of magnitudes more powerful than our star.

This is indeed amazing!
Do you have any sources for that?

And what about that story that ECDSA is not quantum-proof? I suppose that's a "cryptographic flaw" then, meaning that a quantum computer can take a much shorter path than brute force. Is that the case?

[Elwar]

Here's a mathematically, cryptographically proven process for recovering bitcoins sent to a valid but otherwise unintended address. A vanity address generator can be used to reverse-engineer the private key from the (public) address. Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for, at which point you have the private key to reclaim your funds. Of course, you may need to wait several thousand years to find a match. The upside is that, by that time, Bitcoin will surely be the dominant currency in the local extra-solar economy, and your small sum today will certainly be worth quite a bit more due to deflation (only 21 million bitcoins being spread over a multi-planetary market).

Hope this helps.

This. You may want to get started now.

[Nyhm]

Well, Since it's apparently possible to send coins to an address that doesnt exsist, What if it gets created later down the road? Would it "pickup" the funds since the blockchain says "100btc to XYZ was sent 5years ago, OH LOOK! Theres XYZ!, Here you go XYZ!"

Above is correct. To elaborate, "sending" bitcoins is a bit of a misnomer. I've even read introductory tutorials that indicate that the recipient must "claim" the receipt. This is inaccurate and misleading. Here's a more accurate portrayal of a transaction: First, presume that you're Bitcoin client has the private key for an address, which has some bitcoin value assigned to it (from some other address, via the very process about to be described). Your client uses that private key to digitally sign a transaction message, assigning some (or all) of that value to another valid address. This transaction message (tx) gets broadcast to the Bitcoin network at large, where it is eventually accepted into a block on the blockchain, effectively setting it in stone for all time. Notice that your client did not require any knowledge of the recipient beyond a valid address, and there is no action taken by the recipient. The transaction is an irrevocable record that the recipient address (and corresponding private key) now "owns" (has control of, or "is able to transfer") the specified bitcoin value. The only way to re-assign that value to yet another address is by following this same procedure, which requires the private key of the "ownership" address.

Under the original post's scenario, that private key may be unknown to anyone. If anyone ever does generate that key pair (against astronomically incomprehensible odds), they mathematically and cryptographically "own" (because this is how the Bitcoin system is defined) any associated bitcoin value assigned to them by a transaction in the blockchain!

That was a bit long-winded, but my goal was to provide a more narrative description of the process. There are many more details about how transactions can be signed over, but I hope this helps explain the fundamental behavior of the network.

[Raize]

Here's an address:
1BitcoinEaterAddressDontSendf59kuE
While the checksum is valid, it's pretty safe to say that nobody owns the private key

This is incorrect, I have been told on good authority that bulanula owns the private key for that address. 

[foggyb]

A vanity address generator can be used to reverse-engineer the private key from the (public) address. Take the Bitcoin address you accidentally mistyped (which now owns your bitcoins) and put it into a vanity address generator. The generator will create and test private keys until it finds one that produces a public address matching the one you're looking for.

What if there is only a single error (or two) in the address (and I know which character(s)).

Can I vanitygen the key much faster?

[Sekioh]

What if there is only a single error (or two) in the address (and I know which character(s)).

Can I vanitygen the key much faster?

Short answer, not at all.

You'd still be searching for one specific address in the full exponential sea of addresses, number of errors don't matter, just the possible solutions to look for (one) of possibilities (all addresses).