I'm wondering how's possible that the keys are device based keys. Everytime I switch phone I can just do a copy of the messages and Whatsapp will import them wi

I'm wondering how's possible that the keys are device based keys. Everytime I switch phone I can just do a copy of the messages and Whatsapp will import them without issues. The question would be whether that archive also contains the key then and that the keys are not saved in the WhatsApp servers