Sent 0.3 from Bitcoin-Qt. Transaction shows it deducted 0.47!!!

[grewalsatinder]

I just sent 0.3 BTC from Bitcoin-Qt wallet. The transaction showed extra 0.17 BTC sent from my account in that same link! I never sent 0.17 BTC to that address!! Don't even know that address!

What the hell just happened!!!.....

Link: https://blockchain.info/tx/3a739f3f11ffa3f465b4e4fe8b29e905db89c03636cb908c4b59bc618bf28b89 I have uninstalled Bitcoin-Qt and the database!!!...

Was supporting the ledger, but now I won't!

[luv2drnkbr]

That was another address in your own wallet.  That's called a "change address".  When you spend bitcoin, you MUST spend all of an "input", which is money you received elsewhere.

All Bitcoin is is a chain of transactions going from A to B to C all the way back to when the coins were first minted.  So when you want to send 0.3 to somebody, what you do is you say to the network "hey look I got 0.47 from this transaction before, and I'd like to use it now".  And since you must spend all of it (that's how the protocol works), it sends 0.3 to the person you're sending it to, and the rest back to you (at a different address but one which you still control).  Then later, when you want to send 0.1 to somebody, the tx will use that 0.17 and send 0.1 to somebody, and 0.07 back to a new address of yours.

If you still have the file wallet.dat and haven't deleted it, you can recover your 0.17.  It's in there.

[shorena]

I just sent 0.3 BTC from Bitcoin-Qt wallet. The transaction showed extra 0.17 BTC sent from my account in that same link! I never sent 0.17 BTC to that address!! Don't even know that address!

What the hell just happened!!!.....

Change!

Link: https://blockchain.info/tx/3a739f3f11ffa3f465b4e4fe8b29e905db89c03636cb908c4b59bc618bf28b89 I have uninstalled Bitcoin-Qt and the database!!!...

I hope you kept your wallet.dat

Was supporting the ledger, but now I won't!

Maybe you should take the time to understand what your wallet does before you jump to conclusions based on assumptions.

Change? Yes, change. Think of bitcoins you receive as lumps of gold. You received 0.47838041 BTC in the past as a single lump. Now if you want to spend 0.3 BTC this bigger lump is melted into two smaller ones. One is send to the address you specified and the other one is send back to you as change. How change is handled exactly is different for different wallets. Bitcoin core sends the change to a newly generated[1] address that is part of your wallet.dat. If you enable "coin control" in the options you can see this address by going to the send panel and click "select inputs". You will see it listed with the label (change).

Well... if you still have your wallet.dat. If you deleted everything in a fit of rage you essentially deleted your chance to get the coins back.

[1] its not actually generated at that moment, but in advance and hidden from your sight until its needed.

[grewalsatinder]

Thanks for the replies guys.

I was totally frustrated at that moment.

Deleted the Bitcoin-Qt from Applications, and deleted the folder 'Bitcoin' from '~/Library/Application Support/'. And trashed it. 

I orignally use Blockchain.info wallet, and was thinking about testing Bitcoin Qt, so imported private key to Bitcoin Qt and used it to send some BTC.

I thought Bitcoin-Qt was compromised, and may be some hacker injected their address in between somehow or something similar happened.

I usually just use BlockChain.info wallet and never had such experience.

Do you think I can still recover the BTC? I think No. If so, that's okay. I learned by lesson then. A hard one of course.

[spartacusrex]

That's harsh.. Sorry to hear that. If it's any consolation, we've all lost coins at some point..

And I think you'll find your experience is quite common amongst new Bitcoin users (not using Blockchain.info.. which makes it super simple).. it has a steep and unforgiving learning curve. All the best things in life do 

Welcome to the CLUB!

ps If you ran a mac and had a time machine backup, it 'might' be possible.. ?

[luv2drnkbr]

OP, no you cannot recover it.  :-(  The new "change" address was only in your Bitcoin-QT wallet, and not in the Blockchain.info wallet.  For now, you should probably stick to Blockchain.info or if you want a desktop wallet, something like Electrum.  Electrum in particular gives you a set of words you can write down that will always ensure you can recover your money (as long as you use only the addresses it provides you!)

[grewalsatinder]

That's harsh.. Sorry to hear that. If it's any consolation, we've all lost coins at some point..

And I think you'll find your experience is quite common amongst new Bitcoin users (not using Blockchain.info.. which makes it super simple).. it has a steep and unforgiving learning curve. All the best things in life do 

Welcome to the CLUB!

ps If you ran a mac and had a time machine backup, it 'might' be possible.. ?

Oh yes!! I have my Time machine configured!!!.... let me give it a try!... I totally forgot about it.

[TookDk]

That's harsh.. Sorry to hear that. If it's any consolation, we've all lost coins at some point..

And I think you'll find your experience is quite common amongst new Bitcoin users (not using Blockchain.info.. which makes it super simple).. it has a steep and unforgiving learning curve. All the best things in life do  

Welcome to the CLUB!

ps If you ran a mac and had a time machine backup, it 'might' be possible.. ?

Oh yes!! I have my Time machine configured!!!.... let me give it a try!... I totally forgot about it.

There is a resonable chance you can recover your wallet.dat file. The file is still physical on the drive, until it eventually will be overwritten.
Shut down the computer without further notice, and use another computer to recover the file from your drive.
The more you use your computer the less chance there is for a recovery.  

P.S.
Always backup your wallet.dat file, even if just running tests.

P.S.S
Personally I save all my wallets for historical reason. Not really any good reason to delete them.

[grewalsatinder]

That's harsh.. Sorry to hear that. If it's any consolation, we've all lost coins at some point..

And I think you'll find your experience is quite common amongst new Bitcoin users (not using Blockchain.info.. which makes it super simple).. it has a steep and unforgiving learning curve. All the best things in life do 

Welcome to the CLUB!

ps If you ran a mac and had a time machine backup, it 'might' be possible.. ?

Oh yes!! I have my Time machine configured!!!.... let me give it a try!... I totally forgot about it.

There is a resonable chance you can recover your wallet.dat file. The file is still physical on the drive, until it eventually will be overwritten.
Shut down the computer without further notice, and use another computer to recover the file from your drive.
The more you use your computer the less chance there is for a recovery. 

P.S.
Always backup your wallet.dat file, even if just running tests.

I found my whole 'Bitcoin' folder at '~/Library/Application Support/' through time machine. It's about 37 GB. Copying it to 'Downloads' directory. And it includes wallet.dat file

Do you think it will be fine? What should be next steps then?

[grewalsatinder]

OP, no you cannot recover it.  :-(  The new "change" address was only in your Bitcoin-QT wallet, and not in the Blockchain.info wallet.  For now, you should probably stick to Blockchain.info or if you want a desktop wallet, something like Electrum.  Electrum in particular gives you a set of words you can write down that will always ensure you can recover your money (as long as you use only the addresses it provides you!)

Yea, I have that too, and I also imported the private key into it for BlockChain.info address.

Have a backup of Electrum seed passphrase safe too.

Thanks for reply mate!

[shorena]

-snip-
Do you think it will be fine? What should be next steps then?

As long as you have the wallet.dat, you can recover the private key and thus spend those coins. Instead of downloading the whole blockchain again I suggest you try to restore it to where it was before you deleted it. Not sure how the timemachine works, but thats probably the easiest solution. Restore as much as you can and try to start bitcoin core again. If you can just send the coins to your bc.i wallet.

[grewalsatinder]

-snip-
Do you think it will be fine? What should be next steps then?

As long as you have the wallet.dat, you can recover the private key and thus spend those coins. Instead of downloading the whole blockchain again I suggest you try to restore it to where it was before you deleted it. Not sure how the timemachine works, but thats probably the easiest solution. Restore as much as you can and try to start bitcoin core again. If you can just send the coins to your bc.i wallet.

That's what I'm up to. Once the folder is copied from time machine to my 'Downloads' directory, I'll move it back to '~/Library/Application Support/' Then download Bitcoin-Qt wallet from official website and install it.

I think that would eliminate the need to download the whole blockchain. That's why I copied the whole 37 GB folder. Else I could just copy the wallet.dat file.

[spartacusrex]

Can't you just 'restore' the folder through time machine ?

That's what it's for.. ?

[grewalsatinder]

Can't you just 'restore' the folder through time machine ?

That's what it's for.. ?

Yes, I did a 'restore' from Timemachine. When it asked to choose a location where to restore, I selected 'Downloads'.

[TookDk]

Do you think it will be fine? What should be next steps then?

As said before, you don't need to download the blockchain again.

1. Install bitcoin-core
2. Transfer your recovered wallet.dat to the bitcoin-core folder
3. Launch bitcoin core, Open the debug console
4. run walletpassphrase <passphrase> <timeout>    (you can skip this one of you have not encrypted your wallet file, timeout could be e.g. "300", which is in second)
5. run dumpprivkey 1DXKUMfM9UPqnHFZbvi5R9g7uBRchm8Gio
6. Save the returned private key, and your have recovered your 0.17837798 BTC

Good luck

[grewalsatinder]

Do you think it will be fine? What should be next steps then?

As said before, you don't need to download the blockchain again.

1. Install bitcoin-core
2. Transfer your recovered wallet.dat to the bitcoin-core folder
3. Launch bitcoin core, Open the debug console
4. run walletpassphrase <passphrase> <timeout>    (you can skip this one of you have not encrypted your wallet file, timeout could be e.g. "300", which is in second)
5. run dumpprivkey 1DXKUMfM9UPqnHFZbvi5R9g7uBRchm8Gio
6. Save the returned private key, and your have recovered your 0.17837798 BTC

Good luck

Thank you so much for the steps and all your help guys!

I have recovered the wallet.dat, private key, imported it to Electrum and transferred it back to my original account.

Now, I need to read about this 'Change' address. When did that happen? Since Bitcoin-core 0.10 version or from the beginning? I need to understand this thing, and I best understand from videos. Any related video to this topic?

Cheers!

[TookDk]

Do you think it will be fine? What should be next steps then?

As said before, you don't need to download the blockchain again.

1. Install bitcoin-core
2. Transfer your recovered wallet.dat to the bitcoin-core folder
3. Launch bitcoin core, Open the debug console
4. run walletpassphrase <passphrase> <timeout>    (you can skip this one of you have not encrypted your wallet file, timeout could be e.g. "300", which is in second)
5. run dumpprivkey 1DXKUMfM9UPqnHFZbvi5R9g7uBRchm8Gio
6. Save the returned private key, and your have recovered your 0.17837798 BTC

Good luck

Thank you so much for the steps and all your help guys!

I have recovered the wallet.dat, private key, imported it to Electrum and transferred it back to my original account.

Now, I need to read about this 'Change' address. When did that happen? Since Bitcoin-core 0.10 version or from the beginning? I need to understand this thing, and I best understand from videos. Any related video to this topic?

Cheers!

Alweays great to hear when people recover their lost funds.
Have a nice day

As for the change address, it has been like this at least for 2 years, I am not up to date with the version numbers.

[spartacusrex]

It's ALWAYS been like this.

Glad you got your Coins back.. 

[grewalsatinder]

Got it now.
This video made things clear.

https://www.youtube.com/watch?v=q7CVfucFhNI

[ebliever]

If it makes the OP feel any better, this sort of confusion happens often. It's something that really needs to be explained better in a "what to expect" kind of write-up on using bitcoin wallets.

My own scare (https://bitcointalk.org/index.php?topic=957881.msg10481951#msg10481951) involved:

1. Making a very late-night transaction that I promptly forgot about the following days.
2. Running two instances of a multi-bit wallet on two computers.
3. Creating new public keys (at some earlier time) on one of the instances but not copying them over to the other computer.

Thus, when I did the late night transaction, it used a change address recognized on the computer I was using, but my wallet on the other computer didn't recognize it. Combine that with my being groggy from a night of little sleep and totally forgetting about the transaction I'd done and I quickly convinced myself I'd been hacked. Nope, just a case of being sleepy-stupid combined with the complexities of current bitcoin wallets.