End-to-end, on-device, encryption should be fashioned on the private devices you would like to hold your keys.
i
Your
prime-number-key can decipher jumbled messages & media (
if non-convict) and share this ability with other devices. Chats are encrypted with their own
keyboxes per threadId [recipients, entityCollection+doc.id],
Devices will have to be re-forged by revisiting an active device. If you cannot visit an active device your messages and media will likely be unreadable forever.