For years, the divide between Apple’s iMessage and Android’s messaging platforms has been one of the most visible — and most ridiculed — fault lines in consumer technology. The infamous green bubble, signaling a text sent to or from an Android device, has carried with it not just a color difference but a meaningful degradation in privacy and functionality. Now, with the second developer beta of iOS 18.4, Apple is testing a feature that could fundamentally alter the security posture of billions of cross-platform text messages: end-to-end encryption for RCS conversations between iPhone and Android users.
According to AppleInsider, the iOS 18.4 beta 2 release, seeded to developers on February 21, 2025, includes support for encrypted RCS messaging based on the GSM Association’s updated RCS Universal Profile. This marks the first time that Apple has implemented end-to-end encryption (E2EE) for messages exchanged between its platform and Android devices using the Rich Communication Services protocol, a long-awaited development that privacy advocates and industry observers have been demanding for years.
What RCS Encryption Actually Means for Users
End-to-end encryption ensures that only the sender and recipient of a message can read its contents. Not Apple, not Google, not the wireless carrier, and not any government agency intercepting traffic in transit. Until now, RCS messages sent between iPhone and Android users were encrypted in transit — meaning they were protected from casual interception — but were not end-to-end encrypted. This left a significant gap compared to iMessage conversations between Apple devices, which have featured E2EE since 2011, or WhatsApp and Signal, which encrypt all messages by default.
The new implementation follows the GSMA’s MLS (Messaging Layer Security) protocol, which was formally adopted as part of the updated RCS Universal Profile specification. MLS is an Internet Engineering Task Force (IETF) standard designed to provide efficient, scalable encryption for group messaging. The GSMA announced the updated profile in March 2024, and both Apple and Google publicly committed to supporting it. Apple’s inclusion of the feature in the iOS 18.4 beta cycle signals that a public release could arrive as early as spring 2025, likely alongside the final version of iOS 18.4.
A Long Road From SMS to Secure Cross-Platform Messaging
The history of RCS adoption has been marked by delays, corporate maneuvering, and public pressure campaigns. Google spent years lobbying Apple to adopt RCS, launching a high-profile campaign in 2022 under the banner “Get The Message” that directly called out Apple CEO Tim Cook. At the time, Cook dismissed the effort, suggesting that concerned users should simply “buy your mom an iPhone.” The European Union’s Digital Markets Act and growing regulatory pressure, however, appear to have shifted Apple’s calculus. In November 2023, Apple announced it would support RCS in iOS 18, which shipped in September 2024.
But the initial RCS implementation in iOS 18 was notably incomplete. While it brought features like higher-resolution media sharing, typing indicators, and read receipts to cross-platform conversations, it lacked the encryption that both Apple and Google had promised. Messages sent via RCS between iPhone and Android still bore the green bubble — a visual marker Apple has maintained to distinguish non-iMessage conversations — and did not carry the same privacy guarantees as iMessage threads. As AppleInsider reported, the iOS 18.4 beta now changes that equation by activating E2EE for these RCS exchanges.
How the Beta Implementation Works
In the current beta, users who have RCS messaging enabled will see encrypted conversations indicated within the Messages app. The encryption applies to one-on-one and group messages sent between iPhone and Android devices that support the updated RCS Universal Profile with MLS. Both parties must be on compatible software versions — for Android users, this means a recent version of Google Messages that supports the GSMA’s encryption specification.
Apple’s implementation appears to handle key exchange and session management transparently, without requiring users to scan QR codes or manually verify encryption keys, though verification options may be available for security-conscious users. The encryption covers text messages, media attachments, and other RCS-supported content types. Notably, the green bubble remains for RCS conversations, preserving Apple’s longstanding visual distinction between iMessage and non-iMessage threads. This means that while the privacy gap between blue and green bubbles is narrowing significantly, the social stigma Apple has cultivated around the green bubble persists by design.
Google’s Parallel Efforts and the Carrier Factor
Google has been preparing its own infrastructure for MLS-based RCS encryption. Google Messages has supported proprietary end-to-end encryption for RCS conversations between Android users since 2021, but that implementation used Signal Protocol rather than the GSMA’s standardized MLS approach. Google has indicated it will transition to MLS to ensure interoperability with Apple’s implementation. Reports from 9to5Google suggest that Google has been testing MLS support in recent Google Messages beta builds, though a stable release timeline has not been publicly confirmed.
The carrier dimension adds another layer of complexity. RCS messages are routed through carrier infrastructure, unlike iMessage, which uses Apple’s servers exclusively. For E2EE to work properly, carriers must support the updated RCS Universal Profile and not interfere with the encryption handshake. Major U.S. carriers including Verizon, AT&T, and T-Mobile have expressed support for the GSMA’s updated specifications, but global rollout will depend on carrier-by-carrier adoption. In markets where carriers have been slow to implement even basic RCS, encrypted cross-platform messaging could remain unavailable for some time.
Privacy Implications and the Regulatory Context
The arrival of E2EE for RCS messaging comes at a particularly charged moment in the global debate over encryption and law enforcement access to communications. In the United States, the FBI and other agencies have historically pushed for backdoor access to encrypted messaging platforms, arguing that E2EE hampers criminal investigations. The expansion of encryption to cover the massive volume of cross-platform messages between iPhone and Android — which collectively represent more than 99% of the global smartphone market — will likely reignite these tensions.
In Europe, the proposed “Chat Control” regulation has sought to require messaging platforms to scan messages for child sexual abuse material, a mandate that is technically incompatible with true end-to-end encryption. Apple’s decision to implement E2EE for RCS could complicate its regulatory positioning in the EU, though the company has previously taken strong public stances in favor of user privacy. Meanwhile, the United Kingdom’s Online Safety Act contains provisions that could theoretically compel companies to undermine encryption, a prospect that prompted Apple to threaten withdrawal of certain services from the UK market in early 2025.
What Remains Unresolved
Several questions remain as the feature moves through beta testing toward a public release. First, it is unclear whether Apple will provide any visual indicator within the Messages app to distinguish encrypted RCS conversations from unencrypted ones — a feature that would help users understand when their messages are protected. Second, the handling of RCS messages in regions where carriers do not support the updated Universal Profile could create a fragmented user experience, where some cross-platform conversations are encrypted and others are not.
There is also the matter of metadata. Even with E2EE protecting message content, metadata — including who is messaging whom, when, and how often — may still be visible to carriers and potentially to Apple and Google. Neither company has provided detailed public documentation on what metadata is collected or retained in the context of encrypted RCS conversations. For users with the highest security requirements, dedicated encrypted messaging apps like Signal will likely remain the preferred option.
The Bigger Picture for Cross-Platform Communication
Apple’s move to encrypt RCS messaging represents a significant, if overdue, step toward closing the privacy gap between iPhone-to-iPhone and iPhone-to-Android communication. For the estimated 1.5 billion iPhone users and 3 billion Android users worldwide, the practical impact could be enormous — assuming carriers and software updates cooperate to enable the feature broadly. The green bubble may not be going away, but the security it represents is about to look very different.
The iOS 18.4 public release is expected in April 2025, based on Apple’s typical beta-to-release timeline. Until then, developers and public beta testers will serve as the proving ground for what could become one of the most significant privacy upgrades in the history of mobile messaging — not because it introduces a new concept, but because it finally extends an existing one to the billions of messages that cross the Apple-Android divide every day.