Bitcoin Secure Multisig Setup (BSMS).

Defines a safe, step-by-step way to set up a multisig wallet, one that needs several keys to spend, across different devices.

If someone tampers with the setup of a shared wallet, they could trick users into sending coins to the wrong address, and leaked details harm privacy. Here a coordinator gathers each signer's key, builds the wallet's description and sends it back, and each signer checks its own key is in it.