New RCS Spec From GSM Association Adds E2EE; Both Apple and Google to Support It

Jess Weatherbed, reporting for The Verge:

iPhone and Android users will be able to exchange end-to-end encrypted (E2EE) RCS messages in the near future thanks to newly updated RCS specifications. The GSM Association announced that the latest RCS standard includes E2EE based on the Messaging Layer Security (MLS) protocol, enabling interoperable encryption between different platform providers for the first time. [...]

“End-to-end encryption is a powerful privacy and security technology that iMessage has supported since the beginning, and now we are pleased to have helped lead a cross industry effort to bring end-to-end encryption to the RCS Universal Profile published by the GSMA,” said Apple spokesperson Shane Bauer. “We will add support for end-to-end encrypted RCS messages to iOS, iPadOS, macOS, and watchOS in future software updates.” [...]

“We’ve always been committed to providing a secure messaging experience, and Google Messages users have had end-to-end encrypted (E2EE) RCS messaging for years,” Google spokesperson Ed Fernandez told The Verge. “We’re excited to have this updated specification from GSMA and work as quickly as possible with the mobile ecosystem to implement and extend this important user protection to cross-platform RCS messaging.”

This is nothing but good news. But it’s wrong to frame this along Google’s lines, that they’ve been there waiting for Apple to support E2EE for RCS. They’ve been waiting for Apple to support RCS at all, yes, and Google has also implemented their own proprietary E2EE layer for RCS. But until now, there was no E2EE specification in the open RCS spec. Now there is. That’s why it’s not just Android ↔︎ iOS RCS messaging that wasn’t able to use E2EE, but even Android ↔︎ Android, unless both devices were using Google’s own Messages app.

I have also noticed recently that Google Messages and Apple Messages now do a pretty good job of supporting each other’s tapbacks. And that hasn’t done anything to really change the green/blue messaging dynamic. Both things are true: RCS makes cross-platform messaging way better and iMessage remains vastly superior to RCS.

What I’m most interested about with Apple’s implementation of RCS encryption is how they’ll indicate it visually in chats. It’s not going to be with blue bubbles. Blue means “iMessage”, not “encrypted” — it just happens to be that iMessage started as a protocol based on end-to-end encryption. There’s no such thing as a non-encrypted iMessage — it’s part of the protocol, and always has been. But what happens when new/updated Android phones support the new RCS encryption spec, and older devices don’t? A lock icon for the encrypted chats? If it were up to me, iOS would drop support for non-encrypted RCS — iOS should use RCS with E2EE for every device that supports it, and fall back to dumb old no-encryption-at-all SMS for all devices that do not.

★ Saturday, 15 March 2025