Cold storage signing - Error: Server did not answer

[myfrogger]

I am on the latest client 3.2.2 and following the cold storage instructions here:  http://docs.electrum.org/en/latest/coldstorage.html

**The only difference is that when creating the transaction in the watch-only wallet, the "save" button is greyed out and now there is an "export" button.  It creates unsigned.txn

When I load unsigned.txn in the offline, air gapped computer (also running the same client version), and click "sign" it gives me the following error:

Code:

Error: Server did not answer

Can Electrum no longer sign transactions offline?  Or am I doing something wrong?

THANKS

[myfrogger]

Edit, I am using multisig when I received the error.

I created a test single signature wallet, and offline signing worked just fine....hmmm.

Any advice how to do multisig in an offline, cold storage environment?

[myfrogger]

Ok, I answered my own question as I am stubborn and won't give up on this.

This is a known issue (https://github.com/spesmilo/electrum/issues/3302)
So basically if using legacy addresses, no development is planned, but using native segwit, offline signing WORKS. 

SomberNight commented on Apr 6 •

(updated: 2018-05-10)

Recap:

    Trezor:
        legacy does not work, no plan to implement support
        ✔segwit works
    KeepKey:
        legacy does not work, no plan to implement support
        segwit: keepkey itself does not support segwit
    Ledger:
        legacy does not work, no plan to implement support
        ✔segwit works
    Digital Bitbox:
        ✔legacy works (because dbb does not want previous transactions)
        ✔segwit works

[nc50lc]

Edit, I am using multisig when I received the error.
I created a test single signature wallet, and offline signing worked just fine....hmmm.
Any advice how to do multisig in an offline, cold storage environment?

Ok, a couple of pointers for you in order to know why is it impossible to make cold storage Multisig electrum wallet.

First, a transactions from a multisig wallet requires signatures from three different private keys, from your wallet and (two?) from "Trusted Coin" services which provides the 2FA security.
It will require your client to connect to the server in order for TrustedCoin to sign the transaction.

Second, when you created the Watch only wallet using your cold-storage's xpub key (master prublic key), it only created a new wallet based on one of the private keys of your wallet, thus, the addresses would be in the legacy format. (confirm this by showing the address tab)

Lastly, if the watch-only wallet is funded and you want to spend it, you can make an Air-Gap Cold Storage or a spendable Electrum wallet using the paired xprv key (master private key) of the xpub key that you have used to make the watch-only wallet.

[Abdussamad]

multisig doesn't necessarily mean that it's a 2fa wallet with trusted coin as a cosigner.

[myfrogger]

Correct---I am not looking to use a 3rd party or give anyone else control over my keys.  That's not what I'm talking about.

I tested sweeping paper wallets and hardware wallets and it just isn't supported with legacy addresses, nor is development planned.  I appreciate the straightforward answer and it makes sense that future development would be toward native segwit wallets. 

I now just need to learn if cold storage with native segwit (bc1 address) has any downside.  I don't understand it as well, can't seem to get block explorers to work, and likely wouldn't receive future forks.  I just need to learn more.

[Abdussamad]

there were some changes in the unsigned tx format so perhaps upgrading electrum on the cold storage wallet system will help. it's mentioned in the change logs: https://github.com/spesmilo/electrum/blob/master/RELEASE-NOTES

[HCP]

Edit, I am using multisig when I received the error.
I created a test single signature wallet, and offline signing worked just fine....hmmm.
Any advice how to do multisig in an offline, cold storage environment?

Is there any chance that the "error" is being generated by the "co-signer pool" plugin? ie. it is trying to send the "partially signed" transaction to the pool for signing by co-signers, but obviously fails because it is an offline, airgapped machine.

Is that plugin enabled by default on all MultiSig wallets? or does the user have to explicitly enable it?