Topic: Wallets : backup, security and change - page 3. (Read 2487 times)

I'm a bit confused :S
From what you said, If I backup my wallet on a usb stick, then I spend some BTC, if I restore my backup, spent BTC will not be there (as it should be) since a digital backup is a backup of the entire wallet, not only one address.
But If I paper backup my wallet (so only one address), then I spend some BTC, if I restore my paper backup, spent BTC will still be there, is that what you are saying ?

But the paperwallet is just basically a private key right ? So that would mean the private key changes after every transaction I make, every BTC I spend ?
I made a try : on blockchain.info, I checked the private key of one of my addresses, I spent 0.001 BTC, then checked again the private key and it is still the same, so If I backup my private key before spending BTC, then delete the address and restore the private key (which is still the same), why would the amount of BTC different ? I don't get this point sorry :S

Or maybe why I don't understand is because of this most clients will send the change to another address, what change ?
Does that mean if you send for example 1.5 BTC from an address where there are 2 BTC, it actually sends 2BTC, then you receive .5 BTC back ? But not necessarily to the address you sent from ? I'm really confused ^^

1)The wallet contains private keys, not "bitcoins". So no it doesn't get corrupted. It will show the updated value.
3)Yeah

4)Yes if you make backups of your blockchain.info wallet and if you use their browser extension so you don't get a hacked javascript
5)What about the paperwallet has another address? Like, you make a paperwallet with a new address and send the coins there from blockchain.info, so blockchain.info never saw that key
6)there are some softwares somewhere in the forum

Note: if you spend some of your bitcoins most clients will send the "change" (bitcoins not spent) to a NEW address. As Largo said, by default wallet.dat file has 100 hidden keys, so usually it is not a problem (unless you make for example 110 transactions and then you restore your old wallet.dat... surprise)
But if you make a paperwallet, then you spend some of the bitcoins on that address, most clients will send the change to another address. But the paperwallet, well, it of course is only 1 key

By default (Bitcoin-Qt client) your Backups will be valid for 100 outgoing transactions or for 100 x clicking new address button.
Or 50 outgoing transactions AND 50 x clicking new address button.
Since both of them will use one of the 100 pre generated addresses in your wallet.dat

You can increase this by using the following commandline:
bitcoin-qt.exe -keypool=1000
This will set the pool of pre generated keys to 1000, so your backup will last longer.

Just use some other wallet for daily transactions so you dont run out of pre generated addresses on your savings wallet.dat

Ok, but let's take an example :
I make several copies, and put one into a safety box at the bank.
I will not go to the bank after every transaction I do right, same for the one buried in my backyard.
So now, If my backups from bank and backyard are 2 weeks old and I've made new transactions since, and if I lose all my other backups, how can I use my 2 weeks old backup ? Because there are not up to date, so what will happen if I restore one of them ? Will I be able to use my BTC ? Will I see the correct balance ? Or what's going on ?

I recommend:

Downloading the newest client and transfer the bulk of your bit-wealth to it. If it is a lot, make several copies of the wallet.dat file and save them to USB sticks. Bury one in your backyard, keep one in your safety deposit box, etc. You might want to rename and encrypt a copy of the file then hide it online somewhere.
I would also transfer a smallish amount to an online wallet. Perhaps at an exchange like MtGox. This can be your easy to spend money.

Hi everyone !
I'm new in all bitcoin thing and I have a few questions.
I've first read about here and there but there are still a few things I'm not sure to understand correctly.
First thing is about backup:
1. From what I understood, if I make a backup of my wallet (wallet.dat) and later make some transactions, then I restore my backup, my wallet can be corrupted ? Since there are bitcoins that should not be there right ?
2. So the right thing to be done should be : restore backup before making any transaction, then backup again right ?
3. Can I make a paper backup of my wallet at blockchain.info, delete the address from blockchain.info, then restore my paper backup later, and everything will be as it was at the moment of the backup ?
Now about security :
4. Is online wallet blockchain.info safe ?
I actually like blockchain.info since it provides good API and iphone app, and of course, I can check my wallet from everywhere and not only my computer.
5. To add more security to blockchain.info, could I do this : If I have "a lot" of bitcoins on blockchain.info, I do the paper wallet thing from 3., is that good or useless or do you have something better ?
6. How can I make a paper wallet from my current address I have on my computer wallet ?

I guess that's it ^^ Thank you people for your help !