Verify an iMessage contact key before a sensitive conversation

iMessage Contact Key Verification helps detect unexpected changes in the cryptographic key associated with a contact's iMessage conversation. It is meant for people who need high confidence that messages reach the intended contact. Enabling it is not the same as proving that a phone number belongs to a person: you must compare the verification code through a trusted route, and Apple says the feature does not prevent ordinary phishing or text scams.

Before you start​

Both people need compatible Apple software and iMessage. Apple may require you to update all devices signed into the account or sign out of iMessage on an incompatible device before enabling verification. Arrange a separate way to reach the contact, ideally in person or by a number already verified independently.

Do it step by step​

1. On iPhone open Settings, tap your name and Contact Key Verification. Turn on Verification in iMessage and follow Apple's compatibility prompts. Avoid signing out of a device before confirming it holds no irreplaceable local messages.
2. Ask the other person to enable the feature too. Confirm that the person is already in Contacts and that you are using the expected iMessage conversation, not a newly supplied address from an unsolicited message.
3. Open the contact's verification details or exchange Public Verification Codes. Compare the complete code using the trusted second channel; reading a code back inside the same unverified chat does not establish identity.
4. Save the verified code in Contacts when offered. Agree on what to do if either person's device or Apple Account changes; recheck the person through the independent channel before sending sensitive information.
5. If iMessage warns that a verification state changed, pause the sensitive conversation. Ask the contact through the known channel whether they changed devices or account settings, then inspect the new code.
6. Keep ordinary scam checks in place: verify payment requests, file links and urgent pleas separately. A verified messaging key does not make every claim written by the account holder true.

Check the result​

The contact's code matches by an independent channel and the conversation shows the expected verification state. Both people know how to respond to a later warning without ignoring it.

If something goes wrong​

If setup fails, check device software and whether all account devices support the feature. Do not silence a mismatch by blindly turning verification off; resolve the account or device change with the person first.

Know the limit​

Key verification addresses one narrow risk in iMessage identity and delivery. It does not verify a person's intentions, stop social engineering, protect SMS conversations or replace account security. Device compatibility and a real independent comparison are essential. Apple Contact Key Verification guide