Key Recovery

In the 2/3 setup, a mobile client acting as a user co-signs with one of the MPC nodes. In case the mobile client has lost key shares, a backup does not exist, or the backup is damaged, the 2/3 setup offers a recovery option unavailable in other setups. The cloud nodes at the infrastructure of the semi-custodial partner can bring in life the second MPC node and with mobile client interaction can recompute the lost share without learning it. This model assumes robust authentication of the mobile client to the MPC cloud nodes with industry standard multi-factor authentication.