Zero-knowledge team collaboration: the only Dropbox + Slack your provider cannot read

The gap most teams fall into Teams often encrypt one half of their work. They adopt a private messenger and keep a provider-readable drive, or they encrypt files and keep discussing them in a chat tool that stores every message in plaintext. The confidential thing is usually the *conversation about* the document as much as the document itself.

Encrypting half of a workflow protects none of it.

What a unified key model gives you - One identity, one key derivation, one recovery kit — not two half-secured systems. - Attachments that stay encrypted when they move from chat into the drive. - Membership as the single access control: room keys and folder keys are wrapped to the same per-member public key. - Offboarding that rotates keys across conversations and files together. - Search that spans messages and files while remaining blind to the server.

How it works, briefly Your password is stretched on the device with Argon2id to derive a master key. That key unwraps a private X25519 key. Room keys and folder keys are wrapped to each member's public key, and every payload — message, attachment, file, mail body — is sealed with XChaCha20-Poly1305, an authenticated cipher, so tampering fails loudly rather than passing silently.

Servers store ciphertext, wrapped keys and metadata. Search runs on HMAC blind indexes computed on your device. Public links carry key material in the URL fragment, which browsers never send to a server, and are gated by a passphrase, with a hard 24-hour maximum lifetime.

What the team actually sees Channels, threads, mentions, reactions, tasks, file drops with previews, galleries, encrypted ZIP downloads, calls with screen sharing, My Drive, Team Drive, Photos, an encrypted mailbox and a secrets vault. Ordinary work; different foundation.

The discipline it demands No provider-side recovery. Every member generates a recovery kit and stores it offline. Shared work lives in team folders keyed to more than one person, so a single departure never orphans data. Endpoints get device management, disk encryption and hardware-backed authentication, because they are where plaintext exists.

Who this is for Teams whose work is genuinely confidential — legal, healthcare, finance, security, creative under NDA, and any consultancy whose clients ask hard questions. If your work is public by nature, mainstream suites will serve you better and cheaper. Choose the constraint that matches your risk.