Block’s new Bitkey is a 2-of-3 multi signature wallet (https://bitkey.world/en-US)
I’ve been reading their white paper, which is a good summary of their intentions, but doesn’t really go into technical details.
Basically, you need 2 of 3 (phone app “mobile key”, hard wallet “hardware key”, their web service “server key”) in order to approve a bitcoin transaction. As I understand it, n-of-m multisignature transactions is natively (and originally) supported by the BTC blockchain.
However, Bitkey also says that you cannot authorize transactions over a personal set spending limit without the hard wallet. (That is, even though “mobile key”+”server key” would be 2-of-3, the transaction still wouldn’t be authorized if it was over my set spending limit).
Is this functionality that is natively supported by the blockchain? (such as by Core) If not (and is just a policy set of Block/Bitkey), in what ways could it fail or be exploited by a malicious actor? Could someone hack/manipulate Block/Bitkey’s servers so that you could still send BTC over the transaction limit without the hard key?
(PS Sorry for the newbie question. I’m a dev but never worked with blockchains before. I’m learning. If there is more technical tutorial/guide on how I could implement multisig wallets with transaction limits in python, I would enjoy learning about that as well).
Thank you.
