> by listing the trusted devices which you're encrypting against More precisely, on a user device: list the contact devices and key fingerprints. Adding a cont

> by listing the trusted devices which you're encrypting against More precisely, on a user device: list the contact devices and key fingerprints. Adding a contact's device: on first exchange show fingerprint and ask for trust then pin the pubkey. Warn should the key change. What remains is for parties to exchange fingerprints in a peer to peer side channel (possibly even physically via bluetooth/qr-code).