Multi-Device Support

Users can be logged in from multiple devices simultaneously. Each device maintains its own E2EE keypair. Messages are encrypted per-device so every active session can decrypt independently.

How it works

Per-Device Keys

Each device generates its own X25519 keypair on first login and registers it with your key directory.

Device Payloads

The SDK encrypts a separate payload for each recipient device, bundled in one protobuf envelope.

Fan-Out Delivery

The server routes each device-specific payload to the correct connection (or offline queue).

Key directory response

Your key directory endpoint returns an array of device keys. The SDK handles this automatically. 

// GET /api/droponair/keys/{userId} returns:
{
  "keys": [
    { "deviceId": "abc-123", "publicKey": "BASE64..." },
    { "deviceId": "def-456", "publicKey": "BASE64..." }
  ]
}

No client code changes: Multi-device is transparent. If the key directory returns multiple keys, the SDK encrypts for all devices automatically.