Quote from: CBit on April 06, 2013, 12:56:27 PM

Hey!

I've read that you recommend doing a clean install of the OS on the offline machine. Why is that? I understand that a computer once connected to the internet may be infected by malware and that that can fuck up it, including the Armory software, but does it pose threat to the coins if they are backuped on paper?

I have an old computer that I'd like to use as an offline wallet. Windows was reinstalled on it some time ago and it was connected to internet after that only for a short period - in essence, it is highly unlikely that it is infected. I do realize a virus can be there. But with paper backup, will the coins themselves be safe?

Thanks!

In terms of safety of your coins, it's more of how many 9's do you want on your 99.999...% security. A machine that was not previously used for Bitcoin and then is disonnected and starts being used is far less vulnerable than one that stays online. But there's no guarantee it didn't pick up some nasty Bitcoin virus that knows how to shuttle data off the system, or compromised your random number generator so an attacker can produce the same wallet your machine does. These things are tiny for someone holding $500 in BTC, but an unnecessary risk for someone holding $100k.

The paper backup doesn't add security from people attacking the machine. It prevents you from losing your coins if your computer is lost, hard-drive crashes, or you forget your passphrase. If someone compromises the offline computer they can still take your coins, and by the time you notice it, it will be too late, regardless of whether you have the paper backup.