DropOnAir SDK for Unity

End-to-end-encrypted comms for Unity (C#): 1:1 / group / cleartext messaging, attachments, broadcast channels, presence, rooms, calls + room signaling, moderation, multi-device, and push. Real-time voice/video is an optional media add-on.

Install (UPM)

Add via Package Manager (git URL) or Packages/manifest.json:

"com.droponair.sdk-unity": "<git-url>#<tag>"

For local development you can point at a path; shipping builds should consume the published package.

Quick start

using DropOnAir;

var client = new DropOnAirClient(new DropOnAirConfig {
    AppId = "YOUR_APP_ID",
    PublicApiKey = "YOUR_PUBLIC_API_KEY",
    // Your backend signs + proxies token exchange (server secret stays server-side):
    TokenExchangeEndpoint = "https://your-backend.example.com/api/droponair/token",
    KeyDirectoryEndpoint  = "https://your-backend.example.com/api/droponair/keys",
});

client.MessageReceived += m => Debug.Log($"{m.FromUserId}: {m.Text}");
await client.ConnectAsync(userJwt);          // userJwt from your auth system
await client.SendMessageAsync("user-123", "hi");

API areas

Connection lifecycle, messaging (1:1 / group / cleartext) + read receipts, attachments (E2EE), broadcast channels, calls (1:1 / group) + room signaling, rooms + SFU tokens, moderation + waiting room, screen-share + recording signaling, multi-device, push. See Runtime/DropOnAirClient.cs.

Voice / video (optional)

Real-time media is an add-on. Install com.unity.webrtc (mesh) and/or LiveKit Unity (SFU), then register an engine:

client.SetMediaEngine(new DropOnAir.Media.MeshMediaEngine());   // 1:1 + group mesh
string callId = await client.StartVoiceCallAsync("user-123");   // invite + start media
// or for a room over the SFU:
client.SetMediaEngine(new DropOnAir.Media.SfuMediaEngine());
await client.JoinRoomWithSfuAsync(roomId);

Without an engine, the SDK still does all call signaling (CallSignalReceived) so you can drive your own media. See Runtime/Media/README.md.

SFU (LiveKit) notes. The SFU engine targets LiveKit Unity v1.3.8 (https://github.com/livekit/client-sdk-unity.git#v1.3.8), which ships native binaries via Git LFS (run git lfs install before importing) and bundles its own WebRTC. It is verified on Unity 6000.0.x. On Unity 6000.4+, two unused screen-capture source files in that release reference a video-capture module that Unity 6000.4 no longer auto-references; comment those two lines out, or stay on 6000.0.x, until LiveKit publishes a 6000.4-compatible tag. The mesh engine (com.unity.webrtc) is bring-your-own: that package is deprecated on Unity 6, so mesh is provided for customers who supply a working WebRTC backend and is not shipped turnkey.

Dependencies (vendored, self-contained)

The package bundles its managed dependencies under Runtime/Plugins, so it works out of the box with no NuGet/native setup:

• Google.Protobuf.dll (3.34.1), the wire-format runtime for Runtime/Proto/Messaging.cs.
• BouncyCastle.Cryptography.dll (2.6.2), pure-managed E2EE primitives (X25519 + HKDF-SHA256 + AES-256-GCM), portable to every Unity target.

If your project already provides either library (e.g. via NuGetForUnity), delete the vendored copy to avoid a duplicate-assembly conflict.

Tests

Tests/ contains EditMode known-answer tests that validate the E2EE crypto is byte-compatible with the other DropOnAir SDKs offline (no relay needed). Run them via Window > General > Test Runner.

Versioning

DropOnAirVersion.SdkVersion moves in lockstep with the other DropOnAir SDKs; ProtocolVersion (6) and PayloadFormatVersion (1) must match the platform.