Encrypted conversations display a padlock icon next to the “delivered” tag under the most recently-sent message, and also on the “Send” button.
Note that Google Message’s E2EE only kicks in when both members in a conversation are using the latest version of the app on devices and mobile networks that support RCS messaging (most do).
All other conversations—including group chats—will be left unencrypted. It’s theoretically possible that group-chat encryption could show up in a future Messages update, but Google hasn’t indicated such a feature is on the way.
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