The thread says it's possible to sign a message with the privkeys of the keyholders. So each one can create a signed message. How can that be done with electrum?
A few things has to be done. Read this[1] on how to recreate redeem script. Then, read this[2]. When you restore, don't do it in the same client you usually use. Do it in a different computer or virtual box or better yet, use live USB without persistence. Remember to use a secure computer when doing this. If not, your wallet could be compromised. When using virtual box, there maybe problems with directory. You can change directory with
electrum --dir <directory>. For windows, do it in the same way you do for Bitcoin core[3] except replacing
-datadir=<directory> with
--dir <directory>After that, create address with xprv key and corresponding xpub key. I don't know any website or web app which helps you do that[4]. So I can't help you in that!
[1]
https://bitcointalk.org/index.php?topic=1989369.msg19830190#msg19830190[2]
https://www.reddit.com/r/Bitcoin/comments/3wyjev/comment/cy0275q[3]
https://en.bitcoin.it/wiki/Data_directory[4] It is just that I only have little technical knowledgeable, maybe not even "little". So wait for somebody else!
Each keyholder has a privkey. He only would be able to access a certain multisig address starting with a 3 through a multisig wallet. And electrum is the only one being able to create this address.
Can bitcoin core sign a message for a multisig address alone just by providing a single privkey for the address? I doubt it somehow. So how would it work signing messages from each keyholder of a multisig address?
You are signing with private keys of public keys used to create your multisig address, which are P2PKH address (starting with '1'. You can see which addresses you want to sign to prove you are in control of that multisig address or send bitcoins from a multisig address with redeem script. Try entering a redeem script in
http://coinb.in/#verify.
Note: Normally, you use m of n-of-m number of addresses to create a multisig address. Thus, you already know which addresses are needed to sign a transaction for it to be valid. Therefore, there isn't a need to do all this. This is for HD multisig wallets.
