Old Version For Cold Storage

[ps1234]

Some time ago I bought some satoshis and installed Electrum v3.x on a fresh install of Windows 10 on a spare laptop, to use as a cold storage setup. This is always off line and only ever used to sign transactions.

I upgraded to a watching version of Electrum to 4.x on an online pc.

The question is, do I ever need to upgrade Electrum on the cold storage laptop, assuming the laptop continues to work?

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[BlackHatCoiner]

The question is, do I ever need to upgrade Electrum on the cold storage laptop, assuming the laptop continues to work?

Well, you know what they say. If it works don't touch it. If it's a version prior 3.3.2, you have to change it, because there's a serious vulnerability, even thought it can't harm air-gapped devices.

[ps1234]

I understand that "if it works don't touch it", and I would prefer not to change the cold storage laptop, which is running Electrum 3.3.8

Assume that I keep the watching version up to date.

Then, how likely is it that the format of transactions, generated by the watching version to be signed, will change? Or, is it 'set in stone' and fixed by the Bitcoin protocols?

[BlackHatCoiner]

Then, how likely is it that the format of transactions, generated by the watching version to be signed, will change?

There's no absolute answer to this. Highly unlikely I suppose, why would the format ever need to be changed? You shouldn't worry about the format of the transactions, but the new features that are added on top of the Bitcoin protocol overtime, and that you can't use in 3.3.8, such as Taproot.

Or, is it 'set in stone' and fixed by the Bitcoin protocols?

I don't think it'll ever will, and even if it does, the network will treat the old format as non-standard. Currently, there are thousands of Lightning channels opened and people who've signed transactions for inheritance. Suddenly rejecting the old format would destroy these applications.

[Pmalek]

You can always download the newest version on your online machine, bring it over to the offline PC with a USB stick, verify the signatures, and install it if everything is ok. I think there was an issue with the signing process for multisigs was there not? If one Electrum app is 4.0 or higher, they all have to be at least 4.0, meaning you can't use Electrum 3.3.8 in this combination. Maybe my brain is playing tricks on me and I am thinking of something else.   

[BitMaxz]

I think it should work if you generated an unsigned transaction from a watch-only wallet's latest version it will generate a PSBT file you can then import it to your electrum 3.8.8 and be able to sign it. And transfer it back to a new Electrum wallet to broadcast.

I don't heard yet that it didn't work but if it didn't work you can able to use coinb.in to generate an unsigned transaction and sign it with your old Electrum wallet.

[nc50lc]

I think it should work if you generated an unsigned transaction from a watch-only wallet's latest version it will generate a PSBT file you can then import it to your electrum 3.8.8 and be able to sign it. And transfer it back to a new Electrum wallet to broadcast. -snip-

Unfortunately, the PSBT export from the latest version down to 4.0.1 aren't compatible with the lower versions 3.3.8 and below.
He either have to downgrade the watching-only wallet into v3.3.8 or upgrade the cold-storage to v4.0.1.

Electrum Release Notes:

# Release 4.0.1 - (July 3, 2020)
-snip-

* Partially Signed Bitcoin Transactions (PSBT, BIP-174) are supported
   (#5721). The previous Electrum partial transaction format is no
   longer supported, i.e. this is an incompatible change. Users should
   make sure that all instances of Electrum they use to co-sign or
   offline sign, are updated together.

[ranochigo]

I don't heard yet that it didn't work but if it didn't work you can able to use coinb.in to generate an unsigned transaction and sign it with your old Electrum wallet.

The serialization of the raw transaction generated by Coinb.in isn't compatible with Electrum for quite sometime. The compatibility issue would likely remain as Electrum decided not to fix it in favour of PSBT and coinb.in doesn't support PSBT and hasn't changed their raw TX serialization.

The previous reply is correct. You need to update your cold storage if you want to maintain compatibility with the format generated by the newer versions.

[Dabs]

I would update the offline cold storage wallet maybe once a year. Or once every two years. I would find the time to do it securely. If it's like version 3, and version 5 came out, I would at least move it to version 4 or something known to be working fine. Otherwise I would just probably update all wallets to the latest stable version at the same time, both cold and watch-only wallets.

There is very little reason not to update the watch-only wallets often enough, like maybe wait a week or a month after the latest version came out. You can take your time too. There is no rush. I just think it's a good idea to update.

[ps1234]

Thanks for the advice.

I'll upgrade. I just don't like touching the cold storage machine, just in case...

But, with the seed phrase, I can always recreate things at any time in the future - or can I?

[nc50lc]

But, with the seed phrase, I can always recreate things at any time in the future - or can I?

Yes the seed phrase is all you need to restore the wallet, it's basically where all of your wallet's private keys are made from.

[hugeblack]

I'll upgrade. I just don't like touching the cold storage machine, just in case...

Personally, I would prefer to read the features of the update, and if I do not need it, there is no need to update that wallet.

In any case, when you update, remember to keep your cold storage as  "air-gapped" (it has not been connected to the Internet and will not be connected) and therefore download the latest version using tails^[1] or any Linux versions, when you need to sign a transaction.


[1] https://electrum.readthedocs.io/en/latest/tails.html