Topic: Lost large number of bitcoins - page 2. (Read 43476 times)

Wow , tough break:'(.  I wish I could help you .

You are correct.

As I was perusing the source code, I got the impression that each time a key is used, the wallet is topped off to have 100 spares.  I could have understood it wrong, but if I understood it correctly, I don't think it's the 101st transaction that gets hosed... it's the 101st transaction since the backup you have.  (e.g. backup at 55 transactions, you'll get hosed if you need key #156).  Someone please correct me if I'm wrong.

That'd be the equivalent of not having a change at all, I believe.
And, well, honestly, I don't know why it was implemented like this. Unless there's something in the protocol that forces an address to be completely spent when it's used as input, I don't see much utility in this change feature.

> There was talk a while ago about building up a sizeable list of addresses
> in the wallet that would be hidden but used for change for future
> transactions.  The benefit there is that if a user backs up his wallet and
> something like this happens after future transactions, his old backup
> will still "contain" all of the bitcoins since it actually has the addresses
> that change coins were sent to.
>
> What ever happened to that idea?  I think it's a good one.

Since this post a year ago, this feature has been implemented as keypools=100. Personally, I think it is a bad idea and does not address the problem, only pushes it off to the 101st address. At that point, users will come to expect certain backup behavior and then one day (presumably when they have more 'real' rather than 'play' money) it doesn't work as expected.

Unless the pool is recycled (change is returned to a random or cycle of addresses) then this is far more dangerous.

I propose, instead, what is expected. The change should be returned to the same address that the BitCoins were sent from.

I understand this decreases deniability/anonymity. But if someone really is paranoid, they should really be laundering money through multiple addresses in random amounts at random intervals. Sending change to a new address is just an obvious 'paper trail' considering all transactions are public, it doesn't take genius investigator to follow the money.

You mean when you lose wallet.dat you should still have your coins? He would have been fine if he didn't erase his HD.

I would like to promote this idea as well (or something similar).  What happened to Stone Man simply should be nearly impossible from the start, regardless of backups.

There was talk a while ago about building up a sizeable list of addresses in the wallet that would be hidden but used for change for future transactions.  The benefit there is that if a user backs up his wallet and something like this happens after future transactions, his old backup will still "contain" all of the bitcoins since it actually has the addresses that change coins were sent to.

What ever happened to that idea?  I think it's a good one.

More than just Accounts, I'd really like total visibility into what bills are in my wallet, the specific transactions in/out, some total register view that has all the details available.  I feel like the UI is a bit dumbed down, and most of the early adopters are curious about the machinery, not just their total balance.

Just my BTC 0.02.

I will 2nd (3rd, 4th... whatever) this suggestion.  This would help the accounting tremendously.

and, stone man, wow, my condolences.

Ta,

I just want to add my voice to those recommending strongly that the client have an "Accounts" Tab showing an Address and amount stored in each Account.

This would be a natural place to add backup functionality and provisos and warnings.

You can get away with backing up without stopping the client if you don't do anything or receive a payment within a few seconds before the backup.  (like 5 seconds)

No, it doesn't usually empty your wallet with each transaction.  It uses the smallest set of coins it can find to add up to near the amount.  In this case, unfortunately, his wallet had a single 9000 BTC bill in it, and it had to break it to get 1 BTC and 8999 BTC change.

Your 'wallet' is more like your own personal bank
It contains many different accounts. (in Bitcoin these are called Addresses)

Each Address has a balance associated with it, how much money is in it.
Your Wallet balance is the sum of all the balances of the Addresses in your wallet.

When you perform a transaction, it empties enough Addresses to make up the required output amount, but since it has to completely empty each Address there is often money left over in this case the 'change' is returned to you at a new Address.

In this case Stone Man did a transaction that sent all the money from 700+ addresses into a single address and therefore had a wallet containing only one Address that had any money in it.

That Address/Account was emptied as part of the 1BTC transaction and the 8999 change was returned to a new Address to which he lost the private key.

If he had not consolidated all his coins into one Address, he would have lost far fewer coins.

I think the moral of the story might be: "Don't put all your eggs in one basket"


No you can't find out which addresses have which balances using the current GUI.

I think it is "very important" information. 
I also think it is important to be able to chose which addresses are the source of transactions.

This is an example of why the wallet metaphor is bad.

Ok, re-reading carefully and checking the referenced thread, I finally understand this in detail. It's not that bitcoin "empties your wallet" at each transaction - it fully empties an address used to send coins. In this particular case, the user had previously sent themselves the 9000 coins in a lump, resulting in all those coins being held at a single address.

So far as I can tell, there is no way from the GUI client to actually get at the information of what coins in your balance are held at what addresses? Given that the addresses are what is "really important" that information might be of value.

My understanding is that it finds an address or addresses that have at least the number of coins you want to send and sends the change to a new address.

So if he had addresses with 1000, 2000, 2500, and 3500. It would have selected one of them (the lowest one?) and sent 1 away and sent all but 1 back to a new address of his. In this case he would not lose them all, just the remainder of what was in that one address.

It appears he had only 1 address with coins in it. This is probably because he got them all from the market in one go. If that is not the case, then I don't know why he would lose them all.

Wait, I'm confused again. I thought the essence of the surprise was that Bitcoin is programmed to "empty your wallet" for EACH transaction. According to the description I read, when you send coins from address A in your wallet to address B externally, the transaction is actually done by sending ALL the coins out from address A, and the ones that aren't going to address B get sent to address C which is your own address - in other words, even if I'm only paying you a single bitcoin out of my 9000, I mail 1 bitcoin to you and 8999 to myself at a new address.

In other words (unless I'm confused), every transaction you make will result in your old, backed-up wallet addresses become emptied out.

You were right before. The reason all of his coins were lost is that he first transfered all ฿9000 to himself, merging them into a single TxIn. If he had skipped that step and gone straight to sending himself ฿1, he would have only lost the smallest payment that he had previously received that was over ฿1.

I think the client needs to communicate TxIns and TxOuts better to the user. I don't know how to do that without being confusing, but there are real privacy, safety, and security implications in which coins the client chooses to transfer.

A simple solution to this would be to store your wallet.dat on an encrypted partition that goes to an S3-based storage system, like Dropbox. They'll keep versions for you on update.

This would make a nice opt-in service that could be sold in the native client as a way to help fund research, by the way. The data storage needs are incredibly small.

News to me is that *all* your coins are at risk.  I thought it was just clumps of coins (previously received transactions) involved in the transaction, not my aggregate balance.  Yikes.

As a countermeasure, I've manually split my wallet up into five new wallets of distributed value.  Now only one is at risk at any given time.

Good to know this, I thougt I was save with my backups, but it could have happened to me to.
Stoneman didn't really do anything stupid.