Full blockchain airgap

[takuma sato]

I want to use a laptop that never connects to the internet to sign transactions but I never liked how it shows 0 BTC. Of course I know about running a node with a watch-only wallet, I just want to be able to see the BTC on the airgap laptop too.

Since I want to keep backups of the full blockchain, I figured okay, I already got the full blockchain on the online laptop, well what if I send the blockchain files every week or so into the airgap computer thought a safe medium like optical media? This way I would have 2 copies of the blockchain, plus I would see the BTC value on the offline laptop too which is nice. I just want to see it as a peace of mind and I want all the transactions properly ordered with date etc (this is not the case with watch-only wallet, where I had to also manually add all the labels)

Anyway, my question is, can I do this and use PSBT as usual? I've read other people do this too and it shouldn't be a problem, your only concern would be to not enter media that could contain malware to move the blockchain files, but this is so incredibly unlikely if done properly. I also sometime apply offline updates to the Linux offline laptop (there are ways to do this offline) so it would be the same careful approach. You can also boot from Tails and move the files that way so you are never using a compromised OS.

Btw, at what rate is the blockchain growing nowadays? This will determine how often I update my offline backup.

[LoyceV]

It sounds like you're going to compromise security for aesthetics. One way or another, this always adds risks, so I wouldn't do it.

[Yamane_Keto]

The main advantage of an air-gapped device is that it reduces your interaction with online environments. you ONLY need raw data signature form the other device, but currently, you need two laptops and additional storage space for both, which is more than the cost of buying a new Hardware wallet.

I think you forgot that you asked this question before.

Most people would have 2 laptops using linux with a distro of choice. The laptop that signs transactions (cold wallet) wouldn't even have wifi card, bluetooth or anything wireless installed. This laptop does not have an updated blockchain. If you use Bitcoin Core I asume you would just install Bitcoin Core, open it, and basically leave it as if it wast trying to synch, but since there is no internet, it never synchs, and you just generate PSBT file and put it on the other Bitcoin Core laptop that has a watch only wallet with a synched blockchain, then broadcast it into the network.

Thing is, I always thought he hot wallet laptop looks kinda "ugly" or offputing, it just looks like you have 0 funds, and its trying to synch, but since there is no internet, it's just there doing nothing.

[MarryWithBTC]

It sounds like you're going to compromise security for aesthetics. One way or another, this always adds risks, so I wouldn't do it.

Copying the full blockchain to an air-gapped device is actually not solving any problem in this set up, it will just add unnecessary complexity. He is going to compromise security for convenience of seeing BTC balance. A watch-only wallet can handle that need.

Since I want to keep backups of the full blockchain, I figured okay, I already got the full blockchain on the online laptop, well what if I send the blockchain files every week or so into the airgap computer thought a safe medium like optical media?

The main principle of air-gap device is to minimize data transfer. Copying data weekly goes against this principle.

To me, copying the entire blockchain regularly just to view balance is inefficient. It is like downloading the whole library just to check one page of a book.

[satscraper]

Btw, at what rate is the blockchain growing nowadays? This will determine how often I update my offline backup.

You asked google answered  

So the growth rate is around 0.2–0.3 GB per day. At that pace  1 TB SSD will become obsolete fairly soon  especially since you need to reserve about 20% of its capacity for overprovisioning to maintain good performance. My node runs on  2 TB SSD, and I keep the second 1 TB SSD as  backup.

[joniboini]

Can't believe 1 TB SSD won't be enough soon. It's such a bad time since pricing is rising too. Well, I guess most people have some spare storage/SSDs if they're serious about running a node.

Anyway, I agree with others. If your issue is just not being able to see your balance, there are other solutions that won't compromise security. Alternatively, accept it as the trade-off.