Signal Automatic Key Verification & Safety Numbers

What does it help verify?

Signal messages use end-to-end encryption by default. Automatic Key Verification checks that account identifiers match their encryption public keys, helping detect inconsistent key information. It is not a switch that turns chat encryption on.

Key transparency combines device checks and independent audits to check that the system presents consistent records. You need not understand the cryptography, but separate two questions: are the connection keys correct, and is the account controlled by the person you know? The latter still requires trusted real-world contact.

Complete an automatic verification

Update Signal, then choose a contact with an existing conversation. Labels may differ slightly by platform; the option is usually on the safety-number screen in the contact’s profile.

1. Open a one-to-one chat and tap the name or avatar at the top to view the contact profile.
2. Choose View Safety Number and find Automatic Key Verification.
3. Tap Automatically Verify. If available and successful, a green checkmark and encryption-verified message appear.

For your first check, compare screens with a friend you know. This makes it easier to distinguish routine changes from situations that need further verification.

Why is it sometimes unavailable?

Automatic contact verification currently requires Signal to know the contact’s phone number. Chats started by username, changed numbers or an outdated stored number can make it unavailable. Incorrect device date or time can also affect checks.

Check that both apps are current and the device time is correct, then consider recent number changes. Do not ask someone to reveal their phone number just to obtain a checkmark. Keep their privacy choices and compare safety numbers manually instead.

Compare safety numbers manually

Each one-to-one chat has a safety number for checking encryption. Open the relevant screen on both devices, scan in person or compare digit groups through another trusted channel. If they match, mark the contact as verified on your device.

For example, before sharing a private document, compare numbers when you meet. If you can only connect remotely, use a channel you already trust. Do not establish identity solely from a screenshot sent by an unfamiliar account.

What should I do when a number changes?

Changing phones or reinstalling often explains a safety-number change, though not every such action changes it. For an unexpected alert, ask about recent device changes and compare the number again.

If you previously marked the number as verified, you must confirm a change manually before sending new messages. Undelivered messages from before the change are not automatically resent. After checking the connection, review what needs resending.

Make verification part of your routine

You do not need to keep checking verification during casual chats. Check proactively before sharing important information, after an unexpected device change or when a request differs sharply from familiar behavior. Confirm the person, then continue.

Use a simple routine: read the alert, contact the person, compare numbers, then continue. It combines the app’s technical checks with a trusted contact channel and makes unfamiliar alerts less confusing. Use the safety-number guide below when needed.