I'm looking into setting up a multisig setup using Sparrow, and wanted to see if anyone can find any flaws in my set up, and potentially accessing my funds if I lose a key.
set up = 2 of 3
Key store 1 = Passport HWW
Key store 2 = Cold Card HWW
Key store 3 = Gordian Seed Tool (mobile hot wallet)
I will set up the Cold Card and Passport as per the instructions in the below video
Seeds for these will be written onto a seed plate (one seed phrase per plate).
After setting up the Gordian Seed Tool and importing to Sparrow/exporting back to the seed tool, I will deposit (the smallest amount possible) into the multisig wallet.
I will then restore the wallet using all 3 seeds to a different cold card and passport device, and import the wallet as a new wallet in Sparrow.
If the funds are available in the wallet, I have the seed phrases all stored correctly. I wipe the original cold card and passport HWWs.
The seed plates for the 2 HWWs will be stored robustly at different physical locations.
I will destroy the copy of the seed phrase for the gordian seed tool.
I will then test spending the BTC on the wallet in 3 separate transactions (signing with all 3 of the possible combinations of the 2 of 3 key stores.) If I can complete these 3 transactions I am satisfied I have the ability to access my BTC should any 1 of the 3 keystores become compromised.
My questions are
- is there any obvious flaw in this sort of storage setup?
and more importantly
- the only other information I will need in the event that one of my keys becomes physically compromised is the xpub/zpub of each of the 3 keys?
Furthermore storing these xpub/zpubs together (whilst it may create a privacy risk) doesn't create a security risk? e.g with each of the 2 seed plates I would store the xpub/zpub for ALL 3 KEYS on an encrypted SD card. If someone somehow managed to gain access to a seed plate (highly unlikely given the robust physical set up, but worst case), they would have access to 1 of the 3 seed phrases, AND access to all 3 xpub/zpubs? This would not give them access to my BTC, and I would still have access to it and could spend it (transfer it to another wallet) when it became apparent one of the seed phrases could be compromised?
I just want to make sure I'm not shooting myself in the foot by using a more sophisticated setup than a standard cold storage. In reality I consider the chance of making a mistake setting up a multisig solution and exponentially more likley threat than standard cold storage becoming compromised.