Electrum 4.0.1 and offline transaction signing

[DanBoyDan]

Hey guys,

I finally decided to give Electrum a try. My setup is as follows:

 - I imported my seed from original Bitcoin wallet to Electrum to an offline computer
 - I installed Electrum on an online computer and there I created a watch only wallet with the master public key I exported from the offline computer

When I want to create a transaction from the online computer, save it to USB and sign it on the offline computer  I do not see anywhere a PREVIEW button as it is described in the Electrum documentation. See the images below:

https://i.ibb.co/LYg78JT/capt1.png

https://i.ibb.co/ZWqGv43/cap2.png

Can someone guide me step by step how to do it in the new version?

[Rath_]

When I want to create a transaction from the online computer, save it to USB and sign it on the offline computer  I do not see anywhere a PREVIEW button as it is described in the Electrum documentation. See the images below:

This has been changed in the recent update. Apparently, the documentation hasn't been updated yet. Instead of 'Preview', click on 'Pay'. Your transaction won't be signed automatically, you will see more details of your transaction. It's a watch-only wallet anyway. If everything looks fine, press 'Finalize' in the bottom-left corner and you should be able to save the transaction.

[NeuroticFish]

Can someone guide me step by step how to do it in the new version?

First of all, I'd advise you try to also play with this Electrum a little on testnet. Testnet coins are for free and with some patience you can check each step.

However, for the current situation, you should:
0. Make sure Advanced preview is set in Preferences.
1. Press Pay, a new window will show up.
2. Check and press Finalize
3. On the new window you have an Export combo-box.


Edit: @BitCryptex: it's not nice to make a partial post and then complete it from/after others have written a complete solution after you.

[Abdussamad]

note you export not save. save will save it to the wallet file.

[bob123]

- I imported my seed from original Bitcoin wallet to Electrum to an offline

Which "original bitcoin wallet" are you talking about?

Has this seed / mnemonic code been generated offline?
If not, there is no reason to use it on an offline computer now.

If you want a cold storage wallet, you need to generate the seed and mnemonic on an offline device. Importing it from an online wallet defeats the purpose of a cold wallet.

[DanBoyDan]

- I imported my seed from original Bitcoin wallet to Electrum to an offline

Has this seed / mnemonic code been generated offline?
If not, there is no reason to use it on an offline computer now.

It was initially generated offline using BitcoinCore, then the private key was imported to Electrum offline.

[HCP]

It was initially generated offline using BitcoinCore, then the seed was imported to Electrum offline.

Bitcoin Core doesn't create seed mnemonics... so I'm not sure what wallet you actually used??!?

There have been a few "scam" wallets that use names similar to "Bitcoin Core" that give pre-generated seeds and will steal funds... specifically this one: bitsblock.io

If you used that website, I would recommend you immediately transfer any funds to a different wallet and then stop using any wallet that you have created with the seed mnemonic you received from it.

[Husna QA]

It was initially generated offline using BitcoinCore, then the seed was imported to Electrum offline.

Bitcoin core does not have a feature to export seeds. There is a dumpprivkey feature to export private keys.
https://bitcoin.stackexchange.com/questions/60162/seed-for-bitcoin-core-qt
https://bitcoin.stackexchange.com/questions/88237/is-there-a-reason-to-why-bitcoin-core-does-not-implement-bip39

Are you sure the seed you got came from Bitcoin Core?

[bob123]

- I imported my seed from original Bitcoin wallet to Electrum to an offline

Has this seed / mnemonic code been generated offline?
If not, there is no reason to use it on an offline computer now.

It was initially generated offline using BitcoinCore, then the private key was imported to Electrum offline.

What exactly did you import into electrum?

A single private key for a single address?
A master private key for all addresses?
Or a mnemonic code (12/24 words) for all addresses?

If the sensitive data has been created offline, you are definitely fine to regard that as a cold wallet.
But what bothers me is that you might have not used the original core since it does not provide you a mnemonic code.

Can you verify that you imported the master private key (starting with xprv.. yprv.. or zprv..) ?

[DanBoyDan]

- I imported my seed from original Bitcoin wallet to Electrum to an offline

Has this seed / mnemonic code been generated offline?
If not, there is no reason to use it on an offline computer now.

It was initially generated offline using BitcoinCore, then the private key was imported to Electrum offline.

What exactly did you import into electrum?

A single private key for a single address?
A master private key for all addresses?
Or a mnemonic code (12/24 words) for all addresses?

If the sensitive data has been created offline, you are definitely fine to regard that as a cold wallet.
But what bothers me is that you might have not used the original core since it does not provide you a mnemonic code.

Can you verify that you imported the master private key (starting with xprv.. yprv.. or zprv..) ?

Hello,

Thanks for all the responses. The community here is great indeed.
As I am not a frequent crypto user I expressed myself wrong because I do not make a big difference between seed and private keys.

What I exported from BitcoinCore and imported into Electrum were the private keys, not the seed words.
I have also verified the executable files with signature so I am pretty sure I am using the original software.

Thanks for all the warnings though, as I already said - great community here and cheers.

[bob123]

~snip~

Then you are good to go 

You might still consider switching to an HD wallet (i.e. using a seed to generate all of your private keys) to make it easier for you to keep a non-digital backup (with an HD wallet for example the mnemonic code: 12/24 words).
With multiple private keys you need to be quite careful when writing them down (assuming you do have an non-digital backup; which you should).
That would be an improvement to your setup