Apple Upgrades iMessage Encryption for Quantum Threat

Apple announced that it is upgrading the end-to-end encryption in iMessage to guard against the threat that future quantum computers may be able to easily defeat today's traditional encryption. Although no such quantum computer is known to exist today, it is possible that today's encrypted messages could be intercepted, stored, and decrypted by a future quantum computer; hence the need to move to post-quantum cryptography (PQC) today. Apple's new "PQ3" messaging protocol does this, along with several other security enhancements. The protocol includes periodic "rekeying", to ensure that even if a one key is compromised, only part of a conversation could be decrypted. It also utilizes a hybrid approach that combines PQC and a more traditional ECC algorithm, so that if flaws are found in the new PQC algorithm, content is still protected by proven ECC encryption. Support for PQ3 is included in iOS 17.4. PQ3 will fully replace the existing protocol within all supported conversations this year.