Bitcoin Forum

I currently use BitcoinQt and Electrum for my wallets. I wanted to invest some money into BTC this weekend and I want to make sure I don't spend it like I like to do.

So I am figuring my best bet is to take the wallet.dat file from my roaming folder (bitcoinQt's .dat file) and throw it on a USB. Of course after I have transferred the BTC I wish to store there.

I also assume I need to have BitcoinQt closed when I move the file over.

To gain access I then just drag my wallet.dat file over to roaming again and open BitcoinQt and it will be able to use this?

What happens when bitcoinQt realizes its wallet.dat file is gone upon reopening it?
- Just creates a new one with 0.00btc balance?
How does bitcoinQt generate the addresses for new wallet.dat files, does it just create a huge random seed and start a new wallet.dat file with that. When it starts up it reads this seed and can generate the private keys from it, somewhat like electrum does?


Would I be better off starting a clean electrum wallet, dumping my btc there, writing down the seed, and destroying the wallet.dat for electrum? (Then just keep a copy of electrum and the seed.txt on a USB?)

Download Armory

Make a offline paper wallet,

Much more safer.

I'd rather have a USB stick, and I'd rather do it myself.


How is their process so much safer than what I am asking?

Because it's cold storage, you're never connected to the internet so no way your keys are compromised.

Armory can't steal your keys because you're never connected to the internet.

How is that different from moving my wallet.dat file to a USB? Is that not also cold storage? USB's aren't connected to the internet either (unless maybe a virus scans new USB devices for wallet files and sends them away).

No just moving your Wallet.Dat to a USB isn't cold storage.

Could you offer an explanation as to how it is not cold storage?

The wallet.dat is where the keys are stored. Moving it to a USB means the only way to access the keys is by inserting the USB into a USB port and reading the file. I don't understand how you don't consider that cold storage...

https://en.bitcoin.it/wiki/Cold_storage says that

It will not be cold storage, as in "private key is secure, by never being written to a computer system storage device and by being generated on a non-internet-accessible computer". Cold storage is a phrase used for the securest of offline Bitcoin addresses, stored as a private key or paper wallet, that are created in a way that the stored copy(s) of the address are the only ones that have ever been recorded.

A simple way to make your own is to boot off a non-persistent live CD with the ethernet cable unplugged, and run a copy of vanitygen to generate a simple phrase address (use a seed file with a couple minutes of keyboard pounding in it). Write down the resulting address/private key on paper, or dump 100 copies of it to your USB stick. Alternately, use a saved copy of the bitaddress web page to generate your address: https://github.com/pointbiz/bitaddress.org

What you are creating instead is a wallet backup. If someone steals or has already stolen your wallet.dat now or in the future, they would be able to spend coins received by the wallet in the past, present, or future, even money you send to "new" addresses. Address information could be recovered off a hard drive, even if the wallet file is deleted or the drive is repartitioned or reformatted insecurely.

If you plan on making a long-term backup, for the purpose of safeguard against data loss, after encrypting with a passphrase, you might consider starting Bitcoin once with a large keypool option such as bitcoin-qt -keypool=2000. This will fill the wallet with future keys that will keep your backup from becoming obsolete for a long time.

Thanks for explaining that to me and not just saying no.


By live CD you mean something like running a .iso or an install disk? (Could I do this on a virtual machine then delete it?)
I am currently looking over vanitygen, I like it, never knew how people got the "special" addresses.
I'll post here again with some more questions when it comes do doing this.

Once I get the private key from vanitygen, how do I go about accessing my coins again?

You can import the keys on to a web wallet such as BlockChain.info and then you can just transfer them out to where ever you want them to go.

Using a live CD is basically theatrics. The way it works is that you download and burn a CD/DVD using your primary OS installation and then boot off that. If your primary installation is compromised then the live CD can also not be trusted. So what's the point?

Using a VM is even worse. If the host system is compromised a VM can also be compromised.

Actually there is no way to do this without touching the Internet. Even if you decide to dedicate an entire computer as your offline wallet PC you will still need to connect to download the OS and bitcoin wallet/client software. If you are using Linux on your "offline" PC you will need to connect regularly to update software or end up in dependency hell.

Just to be pedantic here, I can think of one way that is completely firewalled. You build your own computer using old-skool pre-internet technology (or just dig out that old ZX-Spectrum from the attic) to be sure there are no NSA infected parts inside, code up your own address generator from scratch (I take it you're allowed to refer to the online wallet code and algorithm documentation, perhaps print it out at your local library), make a nice hot cup of tea (it will make a good source of entropy for your hardware RNG), then Bob's your maiden aunt.  ;D

I like this, though I'm not sure if I want to trust my bitcoins to my coding  ::)

I wouldn't use a USB stick, use a SD card instead (more robust). Make a second folder on the card as a backup.

Please realize that your private key could be stolen, if you copy the wallet.dat to your PC. An infection with a trojan or virus is always possible!

Better use an armory cold storage wallet, if possible sign your outgoing transactions with an old PC which will never connect to the internet. If the "trezor" will finally be available, things will get better/easier.