Electrum and Nano S via Offline computer

[ragnar dannesk gold]

Is it possible to use Electrum and a Nano S to sign unsigned transactions via a permanently offline computer?

I am having some trouble with this:

Setup:

With an online computer using Electrum watch-only wallet, Electrum Personal Server, Bitcoin Core, and a USB to save the unsigned transaction to.

Method:

Transaction is created using the UTXO inputs and the output I want. This transaction is then saved to a USB and transported to the offline computer which has the Nano S plugged in.

I have been unable to get unsigned transactions to be signed by Electrum and Nano S on an offline machine (never connected). This seems like something that should be possible? The Nano S is connected (green light on Nano S symbol in Electrum, and Electrum is offline (red circle).

Obviously there is no transaction history in the offline computer, is this causing the issue? If so, it seems odd that this is required.

Error:

"no interface to do request on ... gave up"


I am unsure whether it is due to Electrum not having UTXO's history or due to another part of the set-up requiring a direct connect.


I have read through https://github.com/spesmilo/electrum/issues/3302 and it doesn't seem to be clear either way. It appears that it isn't as straight forward as I'm thinking, but Sombernight states "Ledger:
legacy does not work, no plan to implement support
✔segwit works" and I'm trying it with P2SH so I assume it should work?

Any help would be much appreciated, but please save yourself the lazy non-answer of 'a Nano S is an offline computer'. I am aware of that line of thinking, it isn't answering my question.




Solved: Adding the flag --offline in my Electrum shortcut fixed it and allowed signing the transaction completely offline.

[Rath_]

✔segwit works" and I'm trying it with P2SH so I assume it should work?

Yes, it should work if you move your funds to a nested SegWit address. You will also benefit from slightly lower fees. Some of my funds are on a native SegWit address on my Trezor. I can check for you if it works. It should be the same for Ledger.

[NeuroticFish]

I have read through https://github.com/spesmilo/electrum/issues/3302 and it doesn't seem to be clear either way.

I didn't encounter this issue, but from what I've read here and there, you should:
* make sure you are working with SegWit addresses, else it won't work -> see https://github.com/spesmilo/electrum/issues/3302#issuecomment-379303347
* make sure you run Electrum with --offline flag -> see https://www.reddit.com/r/Electrum/comments/ciieft/issue_with_offline_signing/

I didn't find anybody telling that they've solved this issue by doing this, so I don't know more...

[bitmover]

Method:

Transaction is created using the UTXO inputs and the output I want. This transaction is then saved to a USB and transported to the offline computer which has the Nano S plugged in.

I have been unable to get unsigned transactions to be signed by Electrum and Nano S on an offline machine (never connected). This seems like something that should be possible? The Nano S is connected (green light on Nano S symbol in Electrum, and Electrum is offline (red circle).

I don't the answer to your question.

however, I was thinking about your method and setup.

It is interesting to do what you are trying to do, but I do not see really a reason to do it (only for curiosity or experimental reasons).
When you plug your usd stick from an online computer to your offline computer, you may be infecting it with malware from the online computer.

Doesn't this defeat the whole purpose of an offline computer?

[Rath_]

Doesn't this defeat the whole purpose of an offline computer?

This could be mitigated by using QR codes for loading unsigned transactions and broadcasting the signed ones. Anyway, that's very unlikely to happen and the malware can't do any harm to the Nano S.

[DireWolfM14]

I am unsure whether it is due to Electrum not having UTXO's history or due to another part of the set-up requiring a direct connect.

If you don't have any unspent transactions in your offline wallet, that could be your problem right there.  I've never tried to use a ledger offline, but I did experiment with Electrum and my KeepKey that way when I first got it.  It worked, but I recall running into an issue that was resolved after loading the transactions into my offline wallet.

[bitmover]

Anyway, that's very unlikely to happen and the malware can't do any harm to the Nano S.

I agree, but if OP though like that he wouldn't even use an offline computer after all.

As he said:

...please save yourself the lazy non-answer of 'a Nano S is an offline computer'. I am aware of that line of thinking...

So, he is assuming that a malware from an online enviroment can somehow harm ledger nano.

However, what is the point of this? As an experiment is may be interesting, but it doesn't make much sense to load data from an online computer to an offline computer, as the malware could affect the offline computer this way.

QR codes would make more sense.

[ragnar dannesk gold]

Thank you to everyone who responded.

* make sure you run Electrum with --offline flag

NeuroticFish, you were right.

Adding the flag --offline in my Electrum shortcut fixed it and allowed signing the transaction completely offline.

Thank you very much for your time.