A team of cryptographers, including former Signal developers, has released Encrypted Spaces, a set of open-source code libraries that enable developers to build end-to-end encrypted collaboration apps. The system uses zero-knowledge proofs to allow servers to manage encrypted data without seeing it, paving the way for private group chats, shared documents, and more.
A group of cryptographers, including contributors from Harvard, Microsoft Research, and former developers of the encrypted messaging app Signal, has released a preview of Encrypted Spaces. This open-source system provides a foundation for building end-to-end encrypted collaboration apps that go beyond simple messaging, allowing users to hold group conversations, share files, and manage data collectively while maintaining strong privacy protections.
Key Points
- Encrypted Spaces is an open-source code library for building end-to-end encrypted collaboration apps.
- The system uses zero-knowledge proofs to let servers manage encrypted data without accessing it.
- It includes a change log that syncs updates across all users' devices securely.
- The project is led by former Signal developers and researchers from Harvard and Microsoft Research.
- A prototype app called Spaces demonstrates the technology, though it is not yet ready for production use.
According to Nora Trapp, an engineer at Harvard’s Applied Social Media Lab and former technical lead for Signal, the timing is right for such a system. “These pieces kind of fall into place to leave us with a moment of technological shift where we can inject encryption and privacy,” she said. The team aims to make it easy for developers to add end-to-end encryption to their apps without needing cryptography expertise.
How Encrypted Spaces Works
Traditional end-to-end encryption works well for one-to-one messaging, but collaboration apps with many users face a challenge: the server cannot decrypt data, so it cannot manipulate it centrally. Encrypted Spaces solves this by maintaining a change log on the server that records every modification to encrypted data. Using zero-knowledge proofs, the server can prove to each user’s device that the log is complete and correct without ever seeing the unencrypted content.
Trevor Perrin, cocreator of the Signal protocol, explained that the system can “roll up” changes into a succinct proof, ensuring every user has the latest version without transmitting the entire history. The server also manages cryptographic keys, allowing new users to be invited and access to be revoked, all while keeping data encrypted.
Matt Green, a cryptography professor at Johns Hopkins, reviewed the project and described it as “the Signal protocol for collaboration apps.” He noted that while other tools like Proton and CryptPad offer end-to-end encryption, Encrypted Spaces provides a rigorous, open-source foundation that developers can trust. “If you use this library, you inherit all the security for free,” Green said.
The team released a prototype app called Spaces, which functions like an encrypted Slack or Discord with group notes, calendar, and file storage. However, they caution that it is a research prototype and not yet suitable for everyday use. The code is available for review by cryptography researchers and developers, with the goal of eventually enabling anyone to build secure collaborative apps.