Why Microsoft Teams is not end-to-end encrypted by default (and what to use instead)

The short answer Microsoft Teams encrypts data in transit and at rest, and offers end-to-end encryption for specific one-to-one call scenarios. Channel messages, group chats and files stored through the workspace are not end-to-end encrypted by default: the service holds the keys.

Why it is built that way Because Microsoft 365 customers ask for capabilities that require readable content:

• compliance search and legal hold across a tenant
• retention and deletion policies applied to message bodies
• data loss prevention rules that inspect what is being sent
• information barriers, classification and labelling
• assistant features that summarise threads and documents

Every one of those needs plaintext at some point on the server side. A platform cannot simultaneously guarantee that it cannot read your data and offer to search it for you.

What "end-to-end" actually requires 1. Keys are generated on the device, never sent to the server in usable form. 2. Each recipient gets the message key wrapped to their own public key. 3. The server stores and relays ciphertext with authenticated encryption, so tampering is detectable. 4. There is no escrow, no admin override, no support path to plaintext. 5. Search, previews and notifications are rebuilt to work without server-side plaintext.

Point 5 is where most "encrypted" products quietly stop.

How to verify a claim in ten minutes Ask the vendor: - Where is my master key derived, and with which KDF? - If I lose my password, can your staff restore my files? - What does your database contain for a single message row? - How is a new member added to an existing private channel?

Answers to look for: on the device with a memory-hard KDF; no; ciphertext plus metadata; the room key is re-wrapped to the new member's public key by an existing member.

The alternative shape A zero-knowledge workspace keeps the same daily rhythm — channels, threads, mentions, file drops, calls — but moves the cryptography to the edge. In DRIVUNO, the password is stretched with Argon2id on your device, room and folder keys are wrapped per member with X25519, and payloads are sealed with XChaCha20-Poly1305. Search uses blind indexes built locally. Public links carry key material only in the URL fragment, which browsers never transmit, and expire within 24 hours at most.

Choosing deliberately If your organisation's primary requirement is governance over content, Teams is well designed for that. If your primary requirement is that certain conversations remain unreadable to everyone but their participants, you need a platform that cannot read them — and you need to accept the recovery discipline that comes with it.