Keybase

Keybase is designed to ensure end-to-end encryption and identity verification in online communications and file sharing. At its core, Keybase uses public key cryptography to map social media identities to encryption keys, making it possible to verify the ownership of these identities through publicly auditable proofs. This approach eliminates the need to trust the service itself, as users can verify the proofs independently.

The technical architecture of Keybase involves a client application written in Go with an Electron front end, available on multiple platforms including Windows, Mac, Android, iOS, and Linux. The app integrates with various online identities such as Twitter, Reddit, GitHub, and Hacker News, allowing users to send encrypted messages and share files without needing the recipient's phone number or email address. Keybase's filesystem (KBFS) is divided into public, private, and team folders, with files stored end-to-end encrypted and accessible via a mounted filesystem on Unix-like and Windows systems.

Operationally, Keybase requires careful management of device authorization and key management. Each device running the client app is authorized by a signature made by another device or the user's PGP key, and each device has a per-device NaCl key for cryptographic operations. The system also supports rekeying files and messages based on public proofs, ensuring seamless communication even if the recipient joins Keybase later. However, there are limitations, such as the mobile versions of the client only being able to download files and not mount the filesystem, and potential performance issues with the Android app as reported by users.

Technically, Keybase offers up to 250 GB of free cloud storage, with files stored in an end-to-end encrypted manner. The chat feature allows for real-time messaging with sub-minute delivery times, and the system supports end-to-end encrypted Git repositories. Despite its robust security features, Keybase has faced challenges post-acquisition by Zoom, including user concerns about the transparency of its codebase and occasional bugs in the mobile app. Nonetheless, Keybase remains a powerful tool for secure communication and file sharing, leveraging its open-source nature and transparent identity proof mechanisms to ensure user trust and security.