Playing with multisig: unable to sign

[zeycus]

Hi, I'm playing with a 2 of 3 multisig, trying to get familiar with the technology. What I did was:

1) Initialize 3 different ledgers, as legacy. Copy the master public key seen with Wallet->Information for each of them, with the form xpub...
2) Create a 2 of 3 multisig wallet with Electrum. When asked, I entered the 3 public master keys for each cosigner. It looks fine, a watch-only wallet. In wallet->Information I can see the Master Public Keys entered, in keystore1, keystore2, keystore3. Nothing suspicious.
3) I sent a tiny amount of BTC to the first of the addresses shown in the multisig wallet. Received with no fuss.

So far so good, here is where my problems start. I just wanted to spend that UTXO. I go to send, choose an address to pay to, a transaction is generated. I choose to Pay it, set the target fee, finalize it. Now I want to export it to be signed by the wallets assigned to each ledger. There are several export options: Copy to keyboard, to QR code, etc. I think at this point I tried them all, for instance I can 'copy to clipboard'. Then, in another instance of Electrum open the wallet for the first ledger cosigner, then Tools->Load Transaction->From text, and copy there the content of the clipboard. The transaction is shown perfectly fine, amounts, outputs and all, but the 'Sign' button is grey. And on the top left there is a text saying 'Transaction Unrelated to your Wallet'.

Why is it unrelated, if the public master key is one of the 3 in the 2-of-3 multisig? Why can't I sign? I must be doing something wrong...

Any help, please?

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[o_e_l_e_o]

Creating a multi-sig wallet in Electrum is not simply a case of combining 3 standard xprvs or xpubs. You have to specifically create a multi-sig setup.

Initialize 3 different ledgers, as legacy. Copy the master public key seen with Wallet->Information for each of them, with the form xpub.

This is where you are going wrong. You can't just mash together 3 standard xpubs and create a functioning multi-sig wallet.

You need to create a new wallet, select "Multi-signature wallet", select 2 signatures from 3 co-signers, select "Create a new seed", choose Legacy or SegWit, back up your seed, and then it will give you a multi-sig xpub which you can use. Repeat that process twice more to get your 2 other xpubs.

You can then create a watch-only multi-sig wallet by combining the three xpubs, and the three standard single signatory multi-sig wallets by combining one of the seed phrase with the xpubs derived from the two other seed phrases. You can even create a single wallet capable of signing transactions itself by combining two or even all three seed phrases in to the same wallet, although that obviously defeats the purpose of a multi-sig wallet.

[nc50lc]

Just re-create the co-signer wallets with those standard seeds using the options:
Multi-signature wallet->2/3->I already have a seed->paste the cosigner's seed (I will say "standard" but don't mind it)->Paste the other cosigner's master public keys.
Do this to the other two wallets (using the right seed/keys).

After spending the transaction, I suggest you to make a new wallet with a reliable backup using the correct set-up explained by the above post.
If it's just for testing purposes, that wallet is fine.

[zeycus]

Thank you both, I'll try your suggestions. Anyway I would not mind losing the tiny amount spent in this experiment, I assumed many things could go wrong. I was following a tutorial and it seems they neglected to emphasize your point.

[Abdussamad]

You have to select  multisignature wallet, choose number of cosigners and signatures required and then "use a hardware device". This last step you repeat for each of the ledger devices. Then for the final cosigner you can have it generate a seed for you.

[nc50lc]

Right, @zeycus when you said "ledgers" are you talking about Ledger nano (hardware device)?
If so, the post above is the right setup.

It's just the descriptions and previously done steps in the OP doesn't sound like Electrum set-up with a hardware device.

[pooya87]

Thank you both, I'll try your suggestions. Anyway I would not mind losing the tiny amount spent in this experiment, I assumed many things could go wrong. I was following a tutorial and it seems they neglected to emphasize your point.

you can always use TestNet for experimenting. it has the benefit of having no value so you won't lose anything at all and also you can always create and share the keys online if you were stuck on some step.
for example you could go to https://iancoleman.io/bip39/ then change the coin from "BTC - Bitcoin" to "BTC - Bitcoin TestNet", create and write down 3 master keys (tprv/tpub) then run electrum with --testnet option, build the wallets and send coins.
to get TestNet coins simply search for Bitcoin TestNet faucet, there are always a couple that give you some amount right away.
you should be able to use ledger on testnet too by changing some settings.

[zeycus]

Right, @zeycus when you said "ledgers" are you talking about Ledger nano (hardware device)?
If so, the post above is the right setup.

It's just the descriptions and previously done steps in the OP doesn't sound like Electrum set-up with a hardware device.

Yes, Nano S. Now I followed your instructions, it all worked nicely and I was able to sign with two keys and spend an UTXO, so thanks everyone for your help.

[nc50lc]

Right, @zeycus when you said "ledgers" are you talking about Ledger nano (hardware device)?
If so, the post above is the right setup.

It's just the descriptions and previously done steps in the OP doesn't sound like Electrum set-up with a hardware device.

Yes, Nano S. Now I followed your instructions, it all worked nicely and I was able to sign with two keys and spend an UTXO, so thanks everyone for your help.

Oh, that's for a non-hardware wallet multisig-setup; you need new seeds for your ledger nano devices since you've exposed your current ones.
Then follow Abdussamad's instructions to correctly set-up a multisig wallet using Ledger nano.