Hi,
The protocol between Envoy and Passport Prime is our QuantumLink protocol. It uses post-quantum-secure crypto primitives (ML-KEM, ML-DSA, and ChaCha20-Poly1305). We have a mobile-side library for that coming out shortly as well so your own apps can connect to your Prime app securely.
For backups, using 3 keycards instead of having one share on Envoy is not in the backup flow at the moment, but is in the backlog, likely in v1.4.0. (v1.3.0 is coming soon).
This is our Developers channel, so in you’re in the right place to ask questions! Just create a new topic for each question.