Android users may sometimes see a small lock icon in several places within their conversations in Google Messages. Here’s why that’s a good thing.
Google’s RCS-capable Messages app now comes as the default messaging app on many Android phones, and it’s introduced some new features and symbols for users to get acquainted with — like a little lock icon beside the send button and text timestamp. Google spearheaded the shift to RCS (Rich Communication Services) with the rollout of its own ‘chat features’ starting in 2019, offering a better alternative to the outdated SMS/MMS. RCS allows for an experience more like Apple’s iMessage, with read receipts, typing indicators, and the ability to send larger files.
While Google’s RCS messaging didn’t launch with end-to-end encryption out of the gate, the much-anticipated security feature finally arrived in 2021. And with it came the lock symbol. When this icon appears in a chat, it simply means all involved parties have end-to-end encryption enabled. This form of secure communication ensures no one outside the message sender and recipient can read the texts should they be intercepted, and it automatically kicks in for conversations where all parties are using RCS with Google Messages.
Related: End-To-End Encryption: What It Means & Why It's Important
In addition to the lock icons attached to encrypted texts and the send button, these chats will display a message that reads, “Chatting with [contact name or phone number].” That, too, will have a lock symbol next to it. End-to-end doesn’t work with SMS/MMS, so users who do not have Google’s RCS enabled will not have this protection.
Conversations protected by Google’s end-to-end encryption will also have a shared verification code, which can be found in the chat’s details. This code is unique to each chat, and both participants will have it. To access this code, users should tap the three dots at the top of the chat, tap ‘Details,’ then hit ‘Verify.’ This will show the code, which the sender and recipient can then confirm with each other. In group chats, the same can be done for each member individually from within the conversation details.
End-to-end encryption was a highly demanded feature that users were disappointed to see excluded from the initial release of Google’s RCS messaging. Its eventual introduction was long overdue, and Google has since expanded the protection to include group chats, to users’ relief. With end-to-end encryption, Android users' messages are safe from the prying eyes of carriers and even Google itself.
Source: Google 1, 2

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