I suspect that the encryption on the contacts would prevent a normal CardDAV implementation from being possible. What probably would work fine, and would solve the most common use case, would be to implement a (possibly bi-directional) syncing feature to the Android and iOS apps. That way, users could "push" their ProtonMail contacts into their phone's contact store.
I suspect that the encryption on the contacts would prevent a normal CardDAV implementation from being possible. What probably would work fine, and would solve the most common use case, would be to implement a (possibly bi-directional) syncing feature to the Android and iOS apps. That way, users could "push" their ProtonMail contacts into their phone's contact store.