how exactly do you back up multibit wallet?

[accord01]

I installed multibit and java, created a pw for wallet and then sent .3 bitcoins to it.  I then installed multibit on another computer and ran the same wallet from usb drive on that client, and the address is the still the same, but the .3 balance is not showing up.

Why is that?

[accord01]

Never mind, i did some research and it says that i have to go to tools and synchronize.  At any rate, when i export just the wallet key, to another file, if that file is stolen, does that person have to know my password to use it?

[jim618]

If you exported your private key with a password (recommended) then it is encrypted and an attacker needs the password.

If you exported it without a password then the private key is exported 'naked'. There is a warning message on the GUI if you select this option saying 'Anyone who can read your export file can spend your bitcoin' as a reminder.

[accord01]

i see... one other dumb question... does every .wallet file in the multibit folder essentially contain the same thing, which is your private key used to back up wallet?

i tried opening every .wallet file and they all open the same wallet, so why are there so may .wallet files?

[jim618]

They are backups, as described in:
https://multibit.org/en/help/v0.5/help_fileDescriptions.html

[Bakemono]

So if i have an un-encrypted wallet and decide to encrypt it in a later time all the backups get encrypted as well right?
I mean there are no unencrypted leftovers right?

[jim618]

Yes that is correct.

The unencrypted wallet backups are AES encrypted and given the file extension .wallet.cipher. Once these are written to disk the originals are secure deleted.
You can open these wallets with File | Open Wallet - you just have to specify the password used for the decryption to work.

With the rolling backups when you encrypt a wallet the previous. unencrypted, wallet is stored for a short while (in case the write of the new encrypted wallet fails). This is then secure deleted after a few minutes (when the next transaction/ block arrives or an edit is made).

[RDRoe]

Then 2 more questions  on backing up:

1.  Is there a way to take the KEY and create a QR code for paper backup?  I can print a QR code from a TXT file.  If not, have you thought of adding the PAPER backup to the program.

2.  Using MBit on 2 computers.  What is the best way?  Use the KEY to just open the wallet on the new laptop, or point it to the WALLET files on laptop #1?  Or DON'T DO IT AT ALL!  ?

Thank you very much!

[jim618]

1) You could do this if you wanted to - though I wouldn't advise using an online QR code generator to do it as you are sending your private key to another server.
The main reason it's not in MultiBit is that there isn't camera support in Java and hence you couldn't round trip the QR code back in.

2) I don't advise having the same wallet active on two computers at the same time using MultiBit. It's not really designed for it. You can easily double spend yourself (for instance you are not prohibited from spending before you have synced. If you have a wallet in two places this can easily create problems).

Also people forget (or don't understand) how exactly transactions work and start creating new receiving addresses on different machines and you can soon get into a mess where none of the balances match. It's not worth the hassle.

[RDRoe]

Ok, great information!  Then if I insure that it is only running on one of the 2 systems, it should be ok?  I use each laptop fairly evenly.  If I make sure that the process is NOT running before I fire it up on the next, should I be ok?

[jim618]

Ok, great information!  Then if I insure that it is only running on one of the 2 systems, it should be ok?  I use each laptop fairly evenly.  If I make sure that the process is NOT running before I fire it up on the next, should I be ok?

Personally I would use different wallets on different machines. 'Keeping all ones eggs in one basket' and all that.