End-to-end encrypted · Deniable · Open source

You never said that.

Deniable, end-to-end encrypted messaging for Microsoft Teams. No one can prove what you wrote — not even cryptographically.

Add to Chrome Read the Protocol

What your chat looks like

Three guarantees

Encrypted

Every message is encrypted with AES-256-GCM using keys derived from X25519 Diffie-Hellman exchange. Microsoft sees ciphertext. Your IT admin sees ciphertext. Only your recipient sees plaintext.

Deniable

No digital signatures on messages. Authentication uses shared HMAC keys — any participant could have forged any message. No one can produce cryptographic proof you authored anything.

Ephemeral

Forward secrecy via Diffie-Hellman ratcheting. Each message uses a unique key that is deleted after use. Compromise today reveals nothing from yesterday. Old keys are gone forever.

Setup in 60 seconds

  1. Install the extension

    Add NeverSaid to Chrome or Edge. It detects Microsoft Teams automatically — no configuration needed.

  2. Verify your email

    NeverSaid detects your Teams identity and registers your encryption keys on keys.neversaid.eu. Click the verification link in your inbox.

  3. Click the lock

    A padlock icon appears next to your compose box. Toggle it on. Every message in that chat is now encrypted and deniable. Your contacts with NeverSaid decrypt automatically.

  4. Invite others

    Contacts without NeverSaid see a friendly prompt with a link to install. No key management, no passphrase to remember, no ceremony.

Under the hood

Cryptographic stack

Key exchange
Simplified X3DH (X25519)
Ratchet
Double Ratchet (DH + symmetric)
Encryption
AES-256-GCM
Authentication
HMAC-SHA256 (deniable)
Key derivation
HKDF-SHA256
Signatures
None on messages — by design
Forward secrecy
Per-message key deletion
Implementation
Web Crypto API + @noble fallback
Plausible deniability

Any transcript can be fabricated.

NeverSaid ships a built-in transcript forgery tool. Anyone can generate a cryptographically valid conversation between any two key holders. Real transcripts and fakes are mathematically indistinguishable.

Say what you need to.
Then deny everything.

Free. Open source. Self-hostable. No accounts beyond your Teams email.

Install for Chrome & Edge