Bitcoin Forum

Hello all,

I was hoping someone could help me understand exactly how to sign a P2PKH message using Electrum and the ColdCard MK3 via the MicroUSB as I don't wish to connect the ColdCard to the computer directly.

I followed the instructions here:

https://coldcardwallet.com/docs/microsd#sign-text-file

However the Cold Card will not allow me to specify which address to use sign the message and the one it's pulling for me by default is not the one I want. Also since I'm new to Cold Card and what I would consider a novice with Electrum I went ahead and signed the text message anyway with the address it defaulted to. I noticed that this address was one that wasn't listed in the Electrum view of my Cold Card wallet and furthermore I wasn't sure how to load it into Electrum. 

Any help here would be very much appreciated. Thanks.

So you want to make a signed message using the cold card with the specific address?

According to this post https://www.reddit.com/r/coldcard/comments/mhcpfs/sign_message_with_specific_bitcoin_address/

When creating a message on notepad you need to add a derivation path at bottom of the text.

You can check the right derivation path from Electrum under the addresses tab just right-click the address and click the details you should see the derivation path of that address.

Here's the sample

Did you include the 2nd line of text with the derivation path? If so, what derivation path did you use? ???

Note that the one in the example (m/23/23'/33) is NOT a "standard" Bitcoin derivation path (which would tend to be something like m/44'/0'/0' or m/49'/0'/0' or m/84'/0'/0' etc)


It says in the coldcard docs linked above that it will default to the master key of "m" if a valid derivation path is not supplied. This would probably explain why it doesn't show in Electrum... it probably wouldn't show in any wallet.