i just lost over 100BTC...

[m4rkiz]

i had my private keys on paper, it worked for me OK for a long time so spending become a routine
open multibit classic, create new wallet on ramdisk, export keys, edit file entering my private key,
import keys, send btc, close wallet, delete wallet from ramdisk

i never had a problem with this scenario so i didn't even check if the change came back last couple of times

and last time (the day that my son was born - i have been a bit busy that day ) it didn't came back where i expected, but i only found out today

it happened due to fact that

"When additional private keys are created or imported the second address in the wallet is always used for change."

Code:

source: https://github.com/bitcoin-solutions/multibit/issues/661

and due to recent slight rise in prices i was collecting unspent bits from here and there, imported few keys, transferred few times etc.

for some reason i presumed that change will be always given back to sending address (that was the very reason i choose multibit over regular client back in the days that you could count wallets on fingers of one hand)...

i know that i have only myself to blame, but for f**k sake...

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[unholycactus]

Do you really completely get rid of your wallets once you're done using them?

Unfortunate, but keep in mind Satoshi designed addresses in the optic that they should be only used once. Therefore, it wouldn't make much sense to send the change to the sending address.

[altcoinhosting]

I feel for you man... It was a very painfull lession i presume.

Hopefully, your post will warn others for this problem, so at least your misfortune can save a couple other users from this misage.

[m4rkiz]

i really think i don't have a backup of that - i emptied that wallet while ago and few weeks ago i wanted to verify that balance is 0 and get rid of it so i don't have a dozens of empty wallets

i would never ever expect to loose any btc as i have backup, backup of backup, and backup of backup of backup in different places on multiple media

all it took is one wrong assumption on how software i have been using works and bang

[m4rkiz]

Therefore, it wouldn't make much sense to send the change to the sending address.

true, but when they designing software that will send change to 'old' addresses it would make much much much more sense that sending address is used instead of second key in the wallet, i mean, come on

[shorena]

Therefore, it wouldn't make much sense to send the change to the sending address.

true, but when they designing software that will send change to 'old' addresses it would make much much much more sense that sending address is used instead of second key in the wallet, i mean, come on

IMHO both versions make not much sense, I suspect it was a limitation of Multibit Classic to keep the number of generated keys low. MultibitHD uses a new address for change as it should.

If you checked all backups you might want to search the disks of the computer(s) you use. Data stored is commonly not really deleted until its overwritten. Maybe some of the lost keys can still be found. Its something I would let an expert do though.

[m4rkiz]

If you checked all backups you might want to search the disks of the computer(s) you use. Data stored is commonly not really deleted until its overwritten. Maybe some of the lost keys can still be found. Its something I would let an expert do though.

nope, nothing there, i actually do know a bit about data recovery so i have a habit of wiping unused devices clean as i often handle sensitive data

one and only chance is some old backup, but it is quite far away and i'm not to sure if it is from right time...

i will know tomorrow for sure, but my hopes are very low

[onemorexmr]

If you checked all backups you might want to search the disks of the computer(s) you use. Data stored is commonly not really deleted until its overwritten. Maybe some of the lost keys can still be found. Its something I would let an expert do though.

nope, nothing there, i actually do know a bit about data recovery so i have a habit of wiping unused devices clean as i often handle sensitive data

one and only chance is some old backup, but it is quite far away and i'm not to sure if it is from right time...

i will know tomorrow for sure, but my hopes are very low

have you checked /tmp? dont know multihd well but some apps write to tmp before overwriting an old savefile... so maybe you are lucky that your wallet-on-ramdisk has been temporarly saved there

(although systemd tends to wipe this dir regulary and its often on a ramdisk anyway)

well... best wishes...i just hope you have more wallets in safe places.

[jim618]

To the OP: that is quite a blow I am sure - you must be gutted. Sorry that you have lost such a significant amount of bitcoin.

From your post I think if you used a ramdisk and then destroyed it afterwards the chances of recovery are low. Whenever MultiBit Classic creates or imports a new private key it writes a rolling backup of the wallet and also a timestamped export of the private keys (encrypted). None of these would have survived as they would have been on your ramdisk.



It is of absolutely no use to the OP, but if anyone reading this thread is still importing and exporting their private keys in this fashion:
PLEASE STOP DOING THIS.

Honestly, the whole point of writing MultiBit HD was to get away from managing individual private keys.

If you are doing anything remotely similar to what the OP is doing:
1) Buy yourself a Trezor or KeepKey for Christmas.
2) Migrate to a deterministic wallet like MultiBit HD, Electrum or Mycelium.
3) Stop importing and exporting individual private keys

[jim618]

@m4rkiz I have been thinking about your post and there is one thing you can try.

First, an explanation of why the second address in a wallet is used for change.
When a new wallet is created it is populated with a single, random private key (this is for usability reasons).
This is a brand new private key (= the first private key/ address in the wallet).
When private keys are imported, they are added and become the second, third etc private keys.

The second private key/ address is used for change using the logic that the user just imported it so they are likely to have a copy of it.


I think how you were using MultiBit Classic means that you were creating a new wallet, importing one or more private keys by editing a private key export file and then effectively sweeping your bitcoin to one of your addresses.

You may have sent change to ONE OF THE ADDRESSES YOU SWEPT.

I suggest you go through all the addresses of every private key you have entered into the private key export files and check their balance.  It may be that change has been sent to one of those addresses. As you've swept them I am thinking that you may not have looked.
It's a quick check on somewhere like blockchain.info. Just check the overall balance on that address.

If any of them have a non-zero balance then you've got their private key on your paper wallet and so can recover the bitcoin.

[BitcoinBud44]

Pity stories always seem to include something about a child being born.

I'm sorry for your loss, if true... just an observation.