How do I keep my bitcoins while I reformat my computer?

[Zakcy]

Hi everyone!

I'm just wondering how I can keep my bitcoin wallet while I reformat my computer, because I don't know what a wallet is synchronized to... is it synchronized to my MAC address? My HWID? I'm even afraid of shutting down my Bitcoin client, because I always think that the next time I load it up, it will be reset

But yeah, because I can't login to my bitcoin wallet with credentials, how is it maintained? And I know it synchronizes with a "server", but how does that server identify me?

[Dabs]

Look for the wallet.dat file. Make a copy of that. Reformat your computer. Copy back the wallet.dat file to the bitcoin directory. My experience is with Windows, but this should be true of the other platforms.

[Zakcy]

Yep, I'm using Windows. But that's all it is? Wallet.dat? Wouldn't that leave it vulnerable for someone to edit?

[memvola]

First and foremost, are you using the standard Bitcoin client?

There are no Bitcoin "server"s to speak of, every Bitcoin node is equal. Your coins are kept in a wallet file. It is named 'wallet.dat' and resides in the bitcoin client's data directory: https://en.bitcoin.it/wiki/Data_directory

EDIT: Since there is no copy of your coins outside your wallet file, if this file is lost, they are gone forever! Make redundant backups of this file (e.g. one local, one remote) before you delete it. If you are backing up to somewhere that's accessible by others, make sure that you encrypt it. If you encrypt it, don't ever forget the password. Write it down on a piece of paper if you have to. Keep the backups safe, update them every couple of months, or more often if you make transactions frequently.

Also:
http://bitcoin.stackexchange.com/questions/746/how-should-you-backup-your-wallet
http://bitcoin.stackexchange.com/questions/324/how-can-i-restore-a-wallet-dat-file

[memvola]

Wouldn't that leave it vulnerable for someone to edit?

That's why the client also supports encryption (Settings -> Encrypt Wallet), though in case you forget your passphrase, you won't be able to spend your coins.

Also even if you use encryption, if your computer is compromised, you could lose your coins the moment you enter your passphrase. So make sure the device(s) you use to access your coins are clean.

[finway]

Back your wallet.

[TheStig]

One other solution is transfer to a online wallet like MTGOX or blockchain.info and transfer back when you're done with the reformatting.

[Dabs]

You may not want to copy your wallet to an online service, so the original suggesting is worth considering.

1. find wallet.dat
2. copy it to your USB flash drive, burn it to CD / DVD, compress it, encrypt it, use an impossible password that is 100 letters long.
3. reformat your computer.
4. after re-installing bitcoin, copy back your wallet.dat to where it used to be.

Personally, I would just use WinRAR to compress my wallet.dat file with recovery data and an impossible password which I randomly generated and printed on paper.

Then after restoring the wallet.dat I would delete the rar file and/or burn the paper that contains the password.

I would only use the encrypted rar file, for example, by uploading it to my email. Then deleting that email once the reformat and reinstallation is complete. That way, if anyone else got a hold of the rar file, they would still take forever to crack the password that even I would have burned away.

[legendster]

find and backup the wallet.dat file

[Splicer]

That is pretty amazing/mind blowing.

[yvv]

Yep, I'm using Windows. But that's all it is? Wallet.dat? Wouldn't that leave it vulnerable for someone to edit?

The best way to be safe is to make a paper wallet, tattoo it on your penis, then eat the paper.

[donnyw]

Penis tatoo is great idea, dont forget to tell your family to check your penis to retrieve password in case you die 

[wetjet43]

Any data you don't keep at least 2 backups of is data that you don't care about.

Always backup your backups backups, and you won't have to worry. (yes, that means make 3 copies of everything).

I encrypt my wallet, and store it on a cloud drive somewhere. There's plenty of free companies out there (dropbox, mozy) that give you a few gigs of free space. Get a few of them, that way your wallet will always be safe.

Also, create a gmail email address that you only access to backup and restore you wallet.dat file to. Call it ilovebitcoins398742938@gmail.com (or whatever). Email that account a copy of your ENCRYPTED wallet.dat file, and you'll always have a copy if you need it.