Demystifying MLS: How a New Standard Is Redefining Secure Collaboration

Secure communication has become a critical requirement for modern organizations. As teams grow, work across borders, and rely on constant digital collaboration, leaders need to understand how their communication tools protect sensitive information. This article explains how secure messaging has evolved, what Messaging Layer Security (MLS) brings to the table, and why it matters for businesses today.

History of Secure Communication

End-to-end encryption (E2EE) has long been the benchmark for privacy. It ensures that messages stay only between the sender and the receiver, unreadable by anyone else. But as organizations expanded and collaboration became more dynamic, the systems designed for one-on-one conversations began to show their limits. 

Traditional encryption protocols like the double ratchet protocol, made popular by apps like Signal, were never built for the scale of modern enterprise communication. Double ratchet was built to be a simple and practical mechanism for handling one-to-one conversations. It works well for small groups, but when hundreds or thousands of participants are involved, each using multiple devices, encryption becomes inefficient and slow. Security came at the cost of performance and scale.

This has a direct impact on business operations. Large teams cannot collaborate effectively if encrypted channels slow down, fail to sync, or cannot support the number of people required for critical conversations. As we explain in our guide on how encrypted messaging apps work, traditional encryption models were never designed for large-scale collaboration. Security comes at the cost of performance and scale, and those costs add up in lost time, reduced productivity and limited flexibility.

But that balance is changing.

Why Critical Conversations Need Sovereign Protection

Download the report to understand where traditional tools fail, why encryption alone is insufficient, and how European organizations can protect critical communication with secure-by-design platforms.

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What is MLS (Messaging Layer Security)

MLS is a new global standard developed by the Internet Engineering Task Force (IETF), the same community that defines the internet’s core protocols. Its goal is simple: make E2EE efficient enough to work at any scale.

Traditionally, every participant in a conversation needs an individually encrypted session with each chat member. This creates a complex web of connections growing exponentially. This is how other messengers like Signal, or even WhatsApp, handle E2EE conversations. It’s also why their group sizes are limited to the low hundreds.

Instead of creating separate cryptographic sessions for every participant, MLS manages keys dynamically within a group. For example, if John sends a message in a 400 person group, his device needs to encrypt that message 400 times, once for every recipient. This is slow, and over time his device might even run out of memory. 

With MLS enabled chats, the message only needs to be encrypted once, and then is sent securely to the whole group. This allows security to scale to larger groups, all without compromising on speed or reliability.

The result is a foundation for truly scalable, secure collaboration. MLS makes it possible to host large, fully encrypted group chats and conference calls with the same security guarantees once reserved for private, one-to-one conversations.

Want a visual explanation?

This video offers a great overview of how MLS works in practice:

Wire’s role in building the standard

Wire has been part of the MLS journey from the start. Since 2016, our engineers have contributed to the IETF working group responsible for shaping and finalizing the protocol. That long-term collaboration means Wire has not just implemented MLS, we helped define it. This gives organizations confidence that MLS on Wire is working correctly, stable, and ready to go. When the people who helped define the standard also build the product, security is precise, reliable, and low risk.

For users, this means Wire is not only the first messenger to bring MLS into full production, but also the most experienced team in deploying it. Unlike competitors who are only exploring MLS or planning future support, Wire already delivers it across one-on-one and group communication today.

Today, Wire is the first messenger to bring MLS into production across both one-on-one and group communication. Every conversation, every call, remains fully end-to-end encrypted. Wire supports channels with up to 2,000 participants and calls with up to 150, all secured by MLS. Over time, we will be able to scale to even larger numbers because of MLS and its efficient group key management. This is not possible with older encryption models. This is more than a technical milestone. It’s a new, stronger foundation for when and how encryption can be used.

Being part of the team that built the standard gives our users a significant advantage: faster access to innovation, deeper security expertise, and a future-proof foundation competitors will take years to match.

Leading the next era of secure communication

MLS represents a turning point in how organizations approach digital security. Just as HTTPS transformed the web into an organized platform for global business, MLS is redefining how teams connect and collaborate at scale.

Wire continues to lead this transformation. From shaping the standard to bringing it into production, we are helping define the next era of secure communication, one where privacy and performance are no longer a trade-off.

The future of secure collaboration is here. And it’s built on MLS.

For anyone who wants to dive deeper into MLS, check out our  MLS whitepaper as well as our comprehensive blog post: https://wire.com/en/blog/mls-is-coming-to-wire-app-learn-more

Learn more about how teams are benefiting from Wire’s MLS implementation and what is coming next here.

Or book a demo to see it in action!