Is iMessage end-to-end encrypted?
Yes — iMessage end-to-end encrypts every chat by default, using PQ3 (hybrid P-256 ECDH + ML-KEM/Kyber post-quantum, AES-128-CTR message payloads, AES-256-CTR attachments, ECDSA P-256 signing); replaced the legacy ECIES/RSA scheme starting iOS 17.4 (Feb 2024). Its handshake is also post-quantum (hybrid ML-KEM-768), so it resists a future quantum computer.
End-to-end encryption protects message contents — but not necessarily metadata. iMessage's metadata model is None by design — Apple's IDS and APNs servers see sender/recipient identifiers, timestamps and routing data in cleartext; only message content and attachment bodies are E2EE. Compare it directly with RVNT, which is E2EE by default with a post-quantum handshake and no central server: RVNT vs iMessage.