Check your keys for end-to-end encrypted chats on Messenger

All end-to-end encrypted chats on Messenger are secure. Your messages are encrypted whether or not you compare keys.
Every device in an end-to-end encrypted chat has a special key that’s used to protect the conversation. For example, if you access the chat from both your computer and your phone, each of these devices will have its own special key.
You and whoever you're talking to in an end-to-end encrypted chat are the only people who have unique and matching keys that can access the conversation. No one can read your encrypted messages except the people who have these keys— not even Meta.
You can compare your keys with another person's keys to make sure only your devices have access to your secure conversation.
View your keys
  1. Open the Messenger desktop app.
  2. Click on an end-to-end encrypted chat with someone.
  3. Click .
  4. Click End-to-end Encryption.
Compare your keys with another person's keys
Once you're viewing your keys in your end-to-end encrypted chat:
  1. Click Your keys. Your friend should click your name to show the keys for you on their device.
  2. Compare the keys that your friend sees for you with the keys that you see for yourself.
If the keys match, you know the conversation is secure between these devices. For example:
  • Alyssa clicks Your keys on her computer and sees 123.
  • Her friend Brandon clicks her name on his computer, and he sees 123.
  • This means that the keys for Alyssa and Brandon match, so they know their conversation is secure on these devices.
  • Brandon should check his keys to ensure that his chats are secure too.
The safest way to compare keys is in person, but you can also read the numbers out loud over a call.
Why your keys might change
Keys can change for several reasons. Keep in mind that not all key changes mean something's wrong. For example, a new key can show up when someone:
  • Uninstalls or reinstalls the Messenger app.
  • Resets their phone.
  • Clears their app data.
When keys change, you'll get a security alert in the conversation.
Other ways you can secure your Messenger chat
Before you manually compare keys, you can also:
  • Check your keys to see all the devices you've used in each end-to-end encrypted chat.
  • Count the number of keys you have for a friend and compare it to the number of keys that your friend has for themselves.
  • Log out of any device you don't recognize to remove it from the end-to-end encrypted chat.
Note: If the number of keys for you and your friend doesn't match, it may mean that your device has been offline for a while. You can check that the chat is secure by sending your friend a message and seeing if the keys change. If you're ever unsure if the chat is safe, you should log out of devices you don’t recognize.
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