Technical reference for IT and developers. The business overview is in the company documentation.

Technical specification · for developers

E2EE v1

Specification draft. The goal is for an independent implementation to exchange messages with Meeter without the server reading them.

1. Device keys

identityKey — long-term X25519 (Ed25519 for signatures).
signedPreKey — X25519 plus an identity signature.
oneTimePreKeys — a batch of X25519 keys, issued one at a time.
Public bundle: identity, signed prekey plus signature, N one-time prekeys.

GET /v1/keys/bundle/{wallet} returns the bundle; private keys never leave the device.

2. Session establishment (X3DH)

Sender: DH(identityA, signedPreKeyB), DH(ephemeralA, identityB), DH(ephemeralA, signedPreKeyB), DH(ephemeralA, oneTimePreKeyB). Shared secret → HKDF → root/key. The first message carries isX3DH=true, ephemeralPub, senderIdentityKey, oneTimePreKeyId, dhRatchetKey, previousCounter, senderKeyId.

3. Message envelope

{
  "version": 1,
  "type": 1,
  "senderKeyId": "…",
  "ciphertext": "base64",
  "iv": "base64",
  "ephemeralPub": "base64",
  "senderIdentityKey": "base64",
  "isX3DH": true,
  "oneTimePreKeyId": 123,
  "dhRatchetKey": "base64",
  "previousCounter": 0
}

type: 1 — text, 2 — file/media, 0x54 — meeting invitation, etc. The server does not interpret ciphertext; sizes and timing are metadata.

4. Groups

Sender keys: a participant distributes their sender key to each member through E2EE; messages are signed/encrypted with the sender key. The server sees senderKeyId, the envelope and metadata. A new participant receives the sender key through an E2EE message.

5. Room and media

The room key is 32 random bytes in the #k=<base64url> link fragment; admission is the invite token, and #k= is only the encryption key. The server receives a derived value to verify the password, not the key itself.
Key material (salt/epoch/keyId) is exchanged through signaling; the SFU relays it.
Audio/video are encrypted with Insertable Streams (SFrame-like format: header + nonce + AES-GCM); the server sees ciphertext.
Fail-closed: a frame without a key or with an error is not sent.

6. Test vectors

Test vectors and format freeze are in preparation. Until publication the specification is not considered stable; report discrepancies to security@meeter.me.