<p>One cannot distinguish between saved and lost coins, because it is only possible to prove ownership of a private key, but impossible to prove that a private key is lost. I.e. nobody can tell the difference between whether I just haven't moved my coins for five years or I lost the key.</p>

<p><a href="https://bitcoin.stackexchange.com/questions/181/can-bitcoins-be-counterfeited">Coins cannot be counterfeited.</a> </p>

<p>Coins can only be spend by having access to the private key. Rediscovering a private key, though, is extremely unlikely and due to the <a href="https://bitcoin.stackexchange.com/questions/2847/how-long-would-it-take-a-large-computer-to-crack-a-private-key">amount of computation required</a> most likely not profitable.</p>

CC BY-SA 3.0
2013-10-11T17:41:19.410Z
I'm kind of new to security. But I'm a little lost as to why it is impossible fake a bitcoin. When I store lets say a word as a hash it gives me string that looks random. That string will always be the same for that word, but completely different for other words. Allowing people to compare and find words. I would think the same could be true with btc, especially because it is open source. Can you please explain in more detail
Ben P. Dorsi-Todaro
CC BY-SA 3.0
2013-10-11T18:07:10.300Z
You accurately describe the behavior of a hashing function. However, Bitcoin uses another mechanism called an *[asymmetric key pair](http://bitcoin.stackexchange.com/questions/4675/what-is-a-private-key-and-a-public-key)*. The pair is composed of an address (public key) and a private key. These have the property that one can be used to decrypt what the other encrypted. I.e. if you encrypt something with a private key, everyone can be sure that the message came from the owner of the corresponding address, because they can only read it when they apply said address to decrypt.
Murch
CC BY-SA 3.0
2013-10-11T18:14:09.910Z
The actual bitcoin amounts are stored in the public ledger. In order to make a payment, you sign a message to the network with your private key that you are sending funds from the corresponding address. Payment orders will not be accepted if you didn't use the correct key to sign. Altogether this means that nobody can spend bitcoins from an address unless he is in control of the correct private key. However, the private key cannot be derived from the address. It would have to be guessed, but there are 2^160 possible private keys.
Murch
CC BY-SA 3.0
2013-10-11T18:15:38.737Z
Okay I think I'm understanding a bit more now. So lets say I had an older wallet with transactions and addresses in it. Some sent a BTC to the address in wallet.dat the wallet.dat gets destroyed after the BTC has been received. Because the address and transactions are there, why doesn't the wallet know from the older wallet data there is a missing BTC and update itself. Or does it? IDK and I haven't tested. I'm not sure if you fully understand what I'm saying
Ben P. Dorsi-Todaro
CC BY-SA 3.0
2013-10-11T18:22:17.100Z
By the way I give you kudo's for explaining. I can't do much because I don't have rep but I would up vote you if I could
Ben P. Dorsi-Todaro
CC BY-SA 3.0
2013-10-11T18:31:50.993Z
[The wallet itself only contains the key pairs!](http://bitcoin.stackexchange.com/a/13281/5406) The client only makes information about transactions and funds available by checking your addresses against the current state of the blockchain (which I called public ledger above and stores the complete transaction history). As long as you retain a current backup of your wallet.dat (i.e. your keys), you won't lose anything. You'd just have to re-import your wallet into a new client and synchronize with the network and you'd be fine. That is btw also why you can receive funds while offline.
Murch
CC BY-SA 3.0
2013-10-11T18:34:01.087Z
Interesting. Thank you. That wasn't the case for me. But it is handy to know. For future reference
Ben P. Dorsi-Todaro
CC BY-SA 3.0
2013-10-11T18:37:02.017Z
You'll have to make a wallet backup at least every 100 transactions, in order to be safe, because Bitcoin-QT stores 100 unused addresses at all times. Or you could increase that setting and be safer for a longer time. ;)

If you feel that I answered your question, you could accept my answer. :)
Murch
CC BY-SA 3.0
2013-10-11T13:32:24.107Z
2015-05-04T14:54:08.600Z
2017-04-13T12:47:33.283Z
Murch
<p>Recently my HDD went, losing all of my data. I make backups frequently and luckily only lost 0.02BTC. I tried everything to recover them, but no luck. As I stated it was small amount that wasn't a much for me to pull my hair out. Just bang my head against the wall. And miss out on a day of coffee. </p>

<p>But this got me thinking. Is there a way to find out how many bitcoins in the world are missing? </p>

<p>I'm guessing that about 6000 transactions after all of the bitcoins have been mined, someone may be able to develop some sort of spider, bot or scrapper of some sort that will index the blockchain and make an educated guess by looking at the transactions.</p>

<p>And if that is so wouldn't it be possible to also determine the Bitcoins that are missing and remake or counterfeit the missing bitcoins?</p>

<p>I know Bitcoin uses SHA encryption. But with good computing power, the knowledge of none being made again. Couldn't something like rainbow tables be created to forge the missing bitcoins?</p>

CC BY-SA 3.0
2013-10-11T13:38:32.767Z
Related questions: http://bitcoin.stackexchange.com/questions/484/why-doesnt-bitcoin-return-lost-coins-back-into-the-block-reward http://bitcoin.stackexchange.com/questions/1638/what-could-be-the-consequences-of-many-bitcoins-being-lost-out-of-circulation-if
Murch
CC BY-SA 3.0
2013-10-11T17:43:18.567Z
Well if you count the Dread Pirate Robert's bitcoins as missing (inaccessible indefinitely) then at least 600,000
Loourr
CC BY-SA 3.0
2013-10-11T17:50:27.053Z
I'd be interested how you arrived at the conclusion that his private keys are lost. However, to be certain would require you to prove that he didn't stash a backup of his private keys somewhere or gave another person access to his wealth – which I doubt anyone including DPR would be able to prove.
Murch
<protocol><shrinking-money-supply>
How Many Bitcoins Are Missing?
Ben P. Dorsi-Todaro
# How Many Bitcoins Are Missing?

(Asked by: username_0 on 2013-10-11)

Recently my HDD went, losing all of my data. I make backups frequently and luckily only lost 0.02BTC. I tried everything to recover them, but no luck. As I stated it was small amount that wasn't a much for me to pull my hair out. Just bang my head against the wall. And miss out on a day of coffee.

But this got me thinking. Is there a way to find out how many bitcoins in the world are missing?

I'm guessing that about 6000 transactions after all of the bitcoins have been mined, someone may be able to develop some sort of spider, bot or scrapper of some sort that will index the blockchain and make an educated guess by looking at the transactions.

And if that is so wouldn't it be possible to also determine the Bitcoins that are missing and remake or counterfeit the missing bitcoins?

I know Bitcoin uses SHA encryption. But with good computing power, the knowledge of none being made again. Couldn't something like rainbow tables be created to forge the missing bitcoins?

**Tags:** protocol, shrinking-money-supply

> **Comments:**
> **username_1**: Related questions: http://bitcoin.stackexchange.com/questions/484/why-doesnt-bitcoin-return-lost-coins-back-into-the-block-reward http://bitcoin.stackexchange.com/questions/1638/what-could-be-the-consequences-of-many-bitcoins-being-lost-out-of-circulation-if  
> **username_2**: Well if you count the Dread Pirate Robert's bitcoins as missing (inaccessible indefinitely) then at least 600,000  
> **username_1**: I'd be interested how you arrived at the conclusion that his private keys are lost. However, to be certain would require you to prove that he didn't stash a backup of his private keys somewhere or gave another person access to his wealth – which I doubt anyone including DPR would be able to prove.  

---

## 1 answers

### Answer by username_1 on 2013-10-11. Score: 0 | Accepted answer

One cannot distinguish between saved and lost coins, because it is only possible to prove ownership of a private key, but impossible to prove that a private key is lost. I.e. nobody can tell the difference between whether I just haven't moved my coins for five years or I lost the key.

[Coins cannot be counterfeited.](https://bitcoin.stackexchange.com/questions/181/can-bitcoins-be-counterfeited)

Coins can only be spend by having access to the private key. Rediscovering a private key, though, is extremely unlikely and due to the [amount of computation required](https://bitcoin.stackexchange.com/questions/2847/how-long-would-it-take-a-large-computer-to-crack-a-private-key) most likely not profitable.

> **Comments:**
> **username_0**: I'm kind of new to security. But I'm a little lost as to why it is impossible fake a bitcoin. When I store lets say a word as a hash it gives me string that looks random. That string will always be the same for that word, but completely different for other words. Allowing people to compare and find words. I would think the same could be true with btc, especially because it is open source. Can you please explain in more detail  
> **username_1**: You accurately describe the behavior of a hashing function. However, Bitcoin uses another mechanism called an *[asymmetric key pair](http://bitcoin.stackexchange.com/questions/4675/what-is-a-private-key-and-a-public-key)*. The pair is composed of an address (public key) and a private key. These have the property that one can be used to decrypt what the other encrypted. I.e. if you encrypt something with a private key, everyone can be sure that the message came from the owner of the corresponding address, because they can only read it when they apply said address to decrypt.  
> **username_1**: The actual bitcoin amounts are stored in the public ledger. In order to make a payment, you sign a message to the network with your private key that you are sending funds from the corresponding address. Payment orders will not be accepted if you didn't use the correct key to sign. Altogether this means that nobody can spend bitcoins from an address unless he is in control of the correct private key. However, the private key cannot be derived from the address. It would have to be guessed, but there are 2^160 possible private keys.  
> **username_0**: Okay I think I'm understanding a bit more now. So lets say I had an older wallet with transactions and addresses in it. Some sent a BTC to the address in wallet.dat the wallet.dat gets destroyed after the BTC has been received. Because the address and transactions are there, why doesn't the wallet know from the older wallet data there is a missing BTC and update itself. Or does it? IDK and I haven't tested. I'm not sure if you fully understand what I'm saying  
> **username_0**: By the way I give you kudo's for explaining. I can't do much because I don't have rep but I would up vote you if I could  
> **username_1**: [The wallet itself only contains the key pairs!](http://bitcoin.stackexchange.com/a/13281/5406) The client only makes information about transactions and funds available by checking your addresses against the current state of the blockchain (which I called public ledger above and stores the complete transaction history). As long as you retain a current backup of your wallet.dat (i.e. your keys), you won't lose anything. You'd just have to re-import your wallet into a new client and synchronize with the network and you'd be fine. That is btw also why you can receive funds while offline.  
> **username_0**: Interesting. Thank you. That wasn't the case for me. But it is handy to know. For future reference  
> **username_1**: You'll have to make a wallet backup at least every 100 transactions, in order to be safe, because Bitcoin-QT stores 100 unused addresses at all times. Or you could increase that setting and be safer for a longer time. ;)  If you feel that I answered your question, you could accept my answer. :)  

---

