Signal Alums Launch Platform for Building Private Collaboration Apps
▼ Summary
– Encrypted Spaces extends end-to-end encryption to collaborative apps, functioning as a “Signal protocol for collaboration apps” for complex tools beyond messaging.
– The project releases a code repository for developers, not a ready-to-use app, aiming to simplify building encrypted apps without cryptography expertise.
– It addresses the limitation of encrypted apps where server-side data manipulation is impossible, enabling collaborative data changes on a centralized server while keeping data encrypted.
– A change log records all data changes, syncing each user’s local app to maintain an up-to-date, consistent version across devices.
– Zero-knowledge proofs allow the server to verify change logs and user access without decrypting data, using roll-ups to confirm the current state without sending the full history.
A team of former Signal developers and cryptography experts has unveiled Encrypted Spaces, a new framework designed to help software engineers build private collaboration apps without requiring deep cryptographic expertise. The project reimagines what end-to-end encryption can achieve, moving beyond simple messaging into complex, multi-user tools like shared documents, project boards, and team databases.
“This is essentially the next generation of the Signal protocol, but for tools that are far more sophisticated than just text or voice,” explains Matt Green, a Johns Hopkins computer science professor specializing in cryptography. Green reviewed both the Encrypted Spaces white paper and a prototype application. “They’ve created an architecture for end-to-end encrypted collaboration. Think of it as the Signal protocol for collaborative apps.”
Unlike Signal’s polished, consumer-ready application, the current Encrypted Spaces release is a code repository aimed at cryptography researchers and developers. The long-term goal is to let programmers build their own secure collaborative tools with no background in encryption. “We want to remove every reason a developer might skip end-to-end encryption,” says Trapp, a lead on the project. “It should be so easy that it’s the default choice.”
Solving the Multi-User Encryption Challenge
Traditional end-to-end encryption works well for one-on-one chats because each device holds its own key, and the server simply relays encrypted messages. But for platforms like Slack or Google Docs, where dozens of users need to edit shared data, that model breaks down. Since the server cannot decrypt the information, it cannot process or manipulate it centrally the way unencrypted apps do.
Encrypted Spaces introduces a novel approach. Instead of storing and processing data on the server, the system maintains a change log that records every modification made to the encrypted data over time. Each user’s device downloads this log and applies the changes locally, ensuring every participant sees the same up-to-date version of the shared workspace.
The server never sees the actual content. It uses zero-knowledge proofs, a cutting-edge cryptographic technique, to verify that no changes have been lost or tampered with. This allows the server to prove the integrity of the data without ever decrypting it. A key feature is the zero-knowledge roll-up, which compresses the entire history of changes into a single, succinct proof. “The server can roll up the changes into a small proof that the current state reflects the whole history,” says Perrin, another team member. “It convinces you the log was applied correctly without having to send every single change.”
The system also manages cryptographic keys in a provable way. Zero-knowledge proofs ensure that only authorized users can decrypt or alter data. When a user leaves a group, their access is revoked in a way that can be mathematically verified. New invitees can be given full access to the history or only to content added after they joined, offering flexible privacy controls.
(Source: Wired)
