Apple has announced PQ3, a significant cryptographic update for iMessage, providing Level 3 security with post-quantum cryptography (PQC) for both initial key establishment and ongoing message exchange. This protocol is designed to secure communications against quantum computing threats and has been formally verified for its robust security properties. PQ3 employs a hybrid design, combining current Elliptic Curve algorithms with new post-quantum algorithms, ensuring it’s never less safe than existing protocols. The rollout will begin with upcoming iOS, iPadOS, macOS, and watchOS updates, with iMessage conversations automatically upgrading to PQ3. This protocol represents a major advancement in securing end-to-end encrypted messaging at scale.