Google Messages hints at a future with universal cross-platform secure group chats (APK teardown)

Rich Communication Services (RCS) has a posse. Or, at the very least, a cult of extremely enthusiastic proponents surrounding it, who want to share the good word about universal messaging. In all seriousness, RCS messaging really is packed with potential, and has the possibility to truly level the playing field when it comes to our ability to securely and clearly communicate all across the world, regardless of platform or carrier. Right now, though, implementation is bit irregular (to put it lightly), and key features lack universal support. We wonder if that could be getting better soon, as we discover a small change in Google Messages that might hint at RCS formalizing support for an important end-to-end encryption (E2EE) system.

Earlier this month we shared evidence for Messages starting early work on support for Messaging Layer Security (MLS). That’s a system designed to make E2EE work securely in group chats, and even chats spread across apps and platforms. While that was great to see, at the time there wasn’t any sign that Google’s interest in MLS with RCS would function any differently from its existing approach to E2EE there, implemented as a User Compatibility Exchange (UCE) add-on rather than a core component of the RCS Universal Profile (UP).

It’s not yet much to go on, but in the new Google Messages messages.android_20240719_00_RC00.phone_samsung_openbeta_dynamic build we spot the text:

+g.gsma.rcs.mls.mls-version

We sure could read that as the GSMA (the group overseeing RCS) adopting MLS that’s built right in to RCS proper. And if that’s indeed happening, that could be huge. RCS UCE additions work fine for bringing functionality to a specific group of users, but when you want that group to include everyone, the only way to ensure blanket support is by baking that functionality into the UP. That would mean that even Apple would be doing MLS, as RCS comes to iPhones.

Even if we’re interpreting this label correctly, who knows what it actually reflects? Google could optimistically be getting Messages ready for eventual MLS in the UP while simultaneously prepping its own (presumably faster out-the-door) solution. So while we’re not nearly about to call this one just yet, let’s say we’re open to feeling optimistic.

While it might be too early to say whether or not the GSMA is embracing MLS, Google is definitely moving forward. Looking at this same release of Google Messages, we notice a couple more strings referencing the system:

• Received failed receipt of MLS message delivery
• Received successful receipt of MLS message delivery

Universal Profile or not, Messages appears to be moving full-steam ahead towards bringing MLS group chat security to its own users.