It encrypts it to all the keys with the phone number registered for that user. Because users are switching phones, but keep their number. But each new WhatsApp app gets a new private key, the old key is not shared. This feature was added later, so the old WhatsApp devs wouldn't know.
So it would be trivial to encrypt to the NSA key also, as done on Windows.
alt Hacker News
It encrypts it to all the keys with the phone number registered for that user. Because users are switching phones, but keep their number. But each new WhatsApp app gets a new private key, the old key is not shared. This feature was added later, so the old WhatsApp devs wouldn't know.
So it would be trivial to encrypt to the NSA key also, as done on Windows.