July 19, 2023 An important step towards secure and interoperable messaging Posted by Giles Hogben, Privacy Engineering Director

Most modern consumer messaging platforms (including Google Messages) support end-to-end encryption, but users today are limited to communicating with contacts who use the same platform. This is why Google is strongly supportive of regulatory efforts that require interoperability for large end-to-end messaging platforms.

For interoperability to succeed in practice, however, regulations must be combined with open, industry-vetted, standards, particularly in the area of privacy, security, and end-to-end encryption. Without robust standardization, the result will be a spaghetti of ad hoc middleware that could lower security standards to cater for the lowest common denominator and raise implementation costs, particularly for smaller providers. Lack of standardization would also make advanced features such as end-to-end encrypted group messaging impossible in practice – group messages would have to be encrypted and delivered multiple times to cater for every different protocol.

With the recent publication of the IETF’s Message Layer Security (MLS) specification RFC 9420, messaging users can look forward to this reality. For the first time, MLS enables practical interoperability across services and platforms, scaling to groups of thousands of multi-device users. It is also flexible enough to allow providers to address emerging threats to user privacy and security, such as quantum computing.

By ensuring a uniformly high security and privacy bar that users can trust, MLS will unleash a huge field of new opportunities for the users and developers of interoperable messaging services that adopt it. This is why we intend to build MLS into Google Messages and support its wide deployment across the industry by open sourcing our implementation in the Android codebase.