Here’s a quick rundown of how Smart Vaults work under the covers:

Dependencies (defaults to public relays/nodes)

- Nostr relay (strfry) to share encrypted messages between signers

- Bitcoin core node

- Compile time: BitcoinDevKit and rust-nostr, among others

- Compatible with public relays but leaves non-chain metadata, such as the custom event types.

Event types

- Introduction of several new event kinds

- 9288 - 9295; for types such as shared signers, proposals, policies/vaults, etc.

- See github for more details: https://github.com/coinstr/coinstr/blob/c3cb3f77a1292b420628b05721ca68a5d0114705/crates/coinstr-sdk/src/constants.rs#L9

Signing

- Smart vaults includes a mobile app and desktop app for signing. They can both be connected to the web app via Nostr-Connect (NIP-46).

- The PSBTs are encrypted and relayed to other signers via the Nostr relay.

- Both apps include functionality for Nostr signatures and Bitcoin signatures. The user can also login to web using a browser plugin but of course cannot sign bitcoin transactions with that.

Release

- Desktop application is in open BETA: https://github.com/coinstr/cointr

- iOS mobile app is releasing to TestFlight by mid-August. (DM to be on wait list)

- Web application (advanced vault editor) releases in September.