Draft:Apple PQ3

Apple's PQ3 is a new post-quantum cryptographic protocol designed for use in quantum-secure end-to-end encryption of IMessage. Apple describes PQ3 as the first protocol with "level 3" security.

While not yet generally released, the new protocol is claimed to be put into use in IOS and IPadOS version 17.4, MacOS 14.4 and WatchOS 10.4. Once matured, PQ3 is expected to fully replace the existing ECC protocol.

PQ3 uses Kyber post-quantum public keys, enabling a sender to retrieve keys during the initial key establishment, even when the receiver is offline. Then a periodic rekeying is included.