RCS Messaging: End-to-End Encryption Coming to SMS Successor?

The era of the humble SMS may not be over yet. A feature long-standard in messaging apps like WhatsApp could breathe new life into the aging protocol.

Once, when characters and minutes were carefully counted when writing and calling, SMS was one of the most common forms of short messaging. In the age of WhatsApp, Signal, and Threema, however, it’s rarely used. While you can still use SMS – or its successor, RCS – with your modern smartphones, other apps offer more and more secure features.

Now, the Rich Communication Service (RCS), the official successor to SMS, is stepping up. A crucial feature, familiar to many WhatsApp users, has been missing: end-to-end encryption. This technology encrypts messages – text, voice, video, or image – as they travel across the network. Only the sender and recipient can view the unencrypted messages.

SMS Successor RCS Receives End-to-End Encryption

RCS launched in 2008, and finally, in 2024, it became usable between Android and Apple devices. With the update to iOS 18, Apple enabled RCS as an alternative to iMessage. RCS, unlike SMS (Short Message Service), operates over mobile data. So you need an internet connection.

GSMA, the organization responsible for RCS, already offers encryption software on its website. The problem? Smartphones haven’t yet supported the function. That may be about to change. French leaker Tiino-X83 announced on X (formerly Twitter) that they discovered a hint of end-to-end encryption (E2EE) in the iOS 26.3 Beta 2. This suggests that both software and hardware for RCS end-to-end encryption may soon be ready.

RCS on the iPhone?

Currently, the encryption hasn’t arrived with the stable iOS 26.3. However, the chances of future implementation in both the Apple and Android ecosystems remain. It’s important that internet providers also activate the function.

The move to end-to-end encryption for RCS represents a significant shift in the messaging landscape. For years, SMS has been vulnerable to interception, a concern for privacy and security. While RCS already offered improvements over SMS – higher resolution media, read receipts, and better group chat functionality – the lack of E2EE was a critical gap.

Google has supported end-to-end encryption over RCS for some time, but only for one-to-one conversations or group chats between Android users using the Google Messages app. The new standard, utilizing the Messaging Layer Security (MLS) protocol finalized by the Internet Engineering Task Force in 2023, aims for broader interoperability. According to GSMA Technical Director Tom Van Pelt, “RCS will be the first large-scale messaging service to support interoperable E2EE between client implementations from different providers.”

The addition of end-to-end encryption, coupled with SIM-based authentication, is intended to provide RCS users with a higher level of privacy and security, protecting them from scams, fraud, and other threats. Apple has confirmed its plans to support the updated RCS standard and end-to-end encryption “in future software updates,” though a specific timeline remains unclear. The change could arrive with an update to iOS 18 in the coming months, or it could be held for the iOS 19 update expected this fall.

RCS, originally conceived in 2007, faced early challenges with feature gaps and interoperability. The introduction of the Universal Profile specification in 2016 and its subsequent rollout have been crucial in addressing these issues. RCS is designed as an open industry standard, aiming to improve upon basic text messaging by leveraging the Internet Protocol (IP).

As of 2020, RCS had rolled out across 90 mobile operators in 60 countries, with an estimated 2.5 billion monthly active users as of 2024. The Google Guest program provides RCS functionality through Google Messages on Android even when a carrier doesn’t natively support it, utilizing the Google Jibe backend.