Apple is launching its first post-quantum encryption called PQ3 for iMessage in the iOS and iPad OS 17.4 and macOS 14.4 updates. PQ3 creates a new post-quantum encryption key using the Kyber algorithm and applies post-quantum protections to the creation of encryption keys and the exchange of messages. The update is considered the most significant cryptographic security upgrade in iMessage history and will fully replace existing encryption protocols by the end of the year. PQ3 has been externally assessed by a third-party security company and two groups of academics. The post-quantum protections are an addition to Apple's existing encryption, combining elliptic curve cryptography (ECC) with the new post-quantum primitives. Apple's approach has stronger protections than Signal's current deployment. Deploying post-quantum encryption now, before functional quantum computers exist, can limit the impact of 'harvest now, decrypt later' attacks. Governments, tech companies, and security agencies are increasingly focusing on post-quantum cryptography to protect against potential quantum computing-based attacks. [ef87d2d9]