iMessage (PQ3)

Is PQC enabled? — quick check

App version check (any platform)

# Signal:    Settings → Help → Version
# WhatsApp:  Settings → Help → App info
# iMessage:  Settings → General → About → Software Version

Expected when PQC is ON

Signal 6.47+ / WhatsApp 24.10+ / iOS 17.4+
PQXDH (Signal/WhatsApp) or PQ3 (iMessage) active for new chats.

What you'll see when PQC is OFF

Signal 6.46 / WhatsApp 24.9 / iOS 17.3
Initial key agreement is classical X3DH only.

These apps don't expose a per-chat PQ indicator. The version on both ends is the authoritative answer.

Apple shipped PQ3 in February 2024. PQ3 adds a Kyber-1024 KEM to the initial iMessage key agreement (alongside ECDH P-256) and rotates the post-quantum key material periodically inside the ratchet. Apple categorizes PQ3 as a "Level 3" PQ messenger — both initial agreement and ongoing rekey are quantum-secure.

Required versions

iOS 17.4+
iPadOS 17.4+
macOS 14.4 Sonoma+
watchOS 10.4+
visionOS 1.1+

If both ends of the conversation are on these versions, PQ3 activates automatically.

Verify

On both devices: Settings → General → About shows the OS version.
iMessage does not expose a per-chat PQ3 indicator — Apple keeps it invisible. The official confirmation is the OS version on both ends.
Forensic check: log stream --predicate 'subsystem == "com.apple.imessage"' on macOS shows PQ3 handshake events.

What about SMS / RCS fallback?

Green-bubble (SMS/MMS) traffic has no end-to-end encryption at all. RCS via the carrier uses the GSMA UP 2.x profile, which currently lacks PQ. Keep blue-bubble for any conversation that requires PQ guarantees.

References

Run the check on services iMessage relies on →