iOS 18 Brings RCS to iPhones, Without End-to-End Encryption, Yet ⇥ gsma.com
[…] When messaging contacts who do not have an Apple device, the Messages app now supports RCS for richer media and more reliable group messaging compared to SMS and MMS.
RCS rolled out in a relatively early beta release for my iPhone — perhaps in July — and I have appreciated both typing indicators and read receipts when chatting with friends who do not have iPhones. But none of those conversations have been end-to-end encrypted. That is not a change from when I messaged them over SMS, but it is not an improvement, either. RCS does not specify end-to-end encryption, and Apple, understandably, does not want to support Google’s proprietary implementation.
But it seems at least one — and perhaps both — of those things may be changing.
Tom Van Pelt, GSMA technical director:
While this is a major milestone, it is just the beginning. The next major milestone is for the RCS Universal Profile to add important user protections such as interoperable end-to-end encryption. This will be the first deployment of standardized, interoperable messaging encryption between different computing platforms, addressing significant technical challenges such as key federation and cryptographically-enforced group membership. Additionally, users will benefit from stronger protections from scam, fraud, and other security threats.
This seems like good news. I have friends who do not use iPhones and, while there are lots of messaging app options for our group chats, it also feels odd to keep an app on your phone for the more-or-less dedicated purpose of maintaining a single conversation.
However, I have at least two questions. The first: how will users be able to tell the difference between a private RCS discussion and one which is not end-to-end encrypted? Apple has several visual indicator options. For example, a message thread could have a persistent padlock or bubbles could use a different colour. Both add a layer of visual complexity which could raise questions or add confusion.
Perhaps a simpler choice would be better. The placeholder text in the compose box, for example, now says “Text Message • SMS” or “Text Message • RCS” depending on which protocol is being used. Surely it could also say something like “Encrypted • RCS” and, if Apple wanted to, it could make iMessage threads match with an “Encrypted • iMessage” placeholder.
This is a solvable problem, but it adds a new dimension to Messages. In all versions since iOS 5, conversations with green bubbles are not end-to-end encrypted, and conversations with blue bubbles are. At some point in the future, those categories will become further bifurcated, with some non-iMessage conversations becoming end-to-end encrypted, and some iMessage conversations becoming more securely protected.
My second question: what protocol is becoming standardized? The answer, it seems, might be a version of Google’s own.
Elmar Weber is a general manager at Google:
We’re proud to have offered end-to-end encryption (E2EE) in Google Messages with #RCS since 2020. We believe that #E2EE is a critical component of secure messaging, and we have been working with the broader ecosystem to bring cross-platform E2EE to RCS chats as soon as possible. Google is committed to providing a secure and private messaging experience for users, and we remain dedicated to making E2EE standard for all RCS users regardless of the platform.
Perhaps there is a different standard which will be met by all RCS providers, but it would be reasonable to guess Google’s existing protocol will form the backbone of this effort. Not only has Apple been apparently pressured into adopting RCS — something I wish it had done without dragging its feet so much — it may be implementing some version of Google’s end-to-encryption after all.
Ultimately, the politics of protocols and promulgated specifications are not much concern to users — or me, frankly. What I hope to see is a future in which end-to-end messaging is the standard for one-on-one and small group conversations, without needing to download anything extra. At some point, a conversation in Messages without the protection of end-to-end encryption will be so rare Apple will feel comfortable animating a warning beacon in the app if you so much as think about sending an SMS. Worldwide attempts to subvert or kneecap end-to-end encryption are also an ongoing threat to these improved expectations of privacy.
Update: In July of last year, the Messaging Layer Security protocol was published as a new standard. It will probably be the cross-platform solution to end-to-end encryption.
Also, for clarity, RCS in iOS also depends on carrier support. If you do not see it, perhaps your carrier has not yet rolled it out.