# Use tokens (/en/realtime-media/interactive-live-streaming/build/authenticate-users/use-tokens/unity)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

To protect your business, it is best practice to authenticate every client that joins a channel. This guide explains how to fetch an authentication token from your token server, use it to join a channel, and renew the token when it expires.

## Understand the tech

      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
  
      
When a user attempts to connect to an Agora channel, your game retrieves a token from the token server in your security infrastructure. Your game then sends this token to Agora SDRTN® for authentication. Agora SDRTN® reads the information stored in the token to validate the request.

The following figure shows the call flow you implement to create step-up-authentication with Agora Interactive Live Streaming:

**Token authentication flow**

![token authentication flow](https://assets-docs.agora.io/images/video-sdk/token-authentication.svg)

## Prerequisites

Before starting, ensure that you have:

* Implemented the [Quickstart](../../index.mdx) in your project.

* Deployed a token server using either of the following guides:

  * [Deploy a token server](deploy-token-server.mdx)
  * [Deploy a middleware server](middleware-token-server.md)

## Implement basic authentication

This section shows you how to implement basic authentication by acquiring a token and using it to join a channel.

### Use a token to join a channel

This section shows you how to integrate token authentication in your game.

1. Open the [SDK quickstart](../../index.mdx) project you created earlier.

2. In `joinChannelVideo.cs` replace the contents with the following:

**Sample code for basic authentication**

```cpp
   using UnityEngine;
    using UnityEngine.UI;
    using UnityEngine.Serialization;
    using Agora.Rtc;
    using Agora.Util;
    using Logger = Agora.Util.Logger;

    namespace Agora_RTC_Plugin.API_Example.Examples.Advanced.JoinChannelVideoToken
    {
      public class JoinChannelVideoToken : MonoBehaviour
      {
        // Fill in your App ID and channel name
        public string appID = "<Your App ID>";
        public string channelName = "test";
        public uint localUid = 0;
        internal static string channelToken = "";
        internal IRtcEngine RtcEngine = null;

        internal CONNECTION_STATE_TYPE _state = CONNECTION_STATE_TYPE.CONNECTION_STATE_DISCONNECTED;

        private void Start()
        {

          if (CheckAppId())
          {
            InitEngine();
            JoinChannel();
          }
        }

        internal void RenewOrJoinToken(TokenObject tokenObject)
        {
          if (tokenObject == null || tokenObject.code != 200) {
            Debug.Log("get token failed");
            return;
          }

          JoinChannelVideoToken.channelToken = tokenObject.token;
          if (_state == CONNECTION_STATE_TYPE.CONNECTION_STATE_DISCONNECTED
            || _state == CONNECTION_STATE_TYPE.CONNECTION_STATE_DISCONNECTED
            || _state == CONNECTION_STATE_TYPE.CONNECTION_STATE_FAILED
          )
          {
            // Use the token to join the channel
            JoinChannel();
          }
          else
          {
            // Update token in the channel
            UpdateToken();
          }
        }

        private void Update()
        {
          PermissionHelper.RequestMicrophonePermission();
          PermissionHelper.RequestCameraPermission();
        }

        private void UpdateToken()
        {
          RtcEngine.RenewToken(JoinChannelVideoToken.channelToken);
          Debug.Log("renewToken: " + JoinChannelVideoToken.channelToken);
        }

        private bool CheckAppId()
        {
          if (appID.Length < 10) {
            Debug.Log("Please fill in your appId in Inspector");
            return false;
          }
          return true;
        }

        // Initialization
        private void InitEngine()
        {
          RtcEngine = Agora.Rtc.RtcEngine.CreateAgoraRtcEngine();
          UserEventHandler handler = new UserEventHandler(this);
          RtcEngineContext context = new RtcEngineContext(appID, 0,
            CHANNEL_PROFILE_TYPE.CHANNEL_PROFILE_LIVE_BROADCASTING, null,
            AUDIO_SCENARIO_TYPE.AUDIO_SCENARIO_DEFAULT);
          RtcEngine.Initialize(context);
          RtcEngine.InitEventHandler(handler);
        }
        // Join channel
        private void JoinChannel()
        {
          RtcEngine.SetClientRole(CLIENT_ROLE_TYPE.CLIENT_ROLE_BROADCASTER);
          RtcEngine.EnableAudio();
          RtcEngine.EnableVideo();

          if (channelToken.Length == 0)
          {
            StartCoroutine(HelperClass.FetchToken(this.localUid, channelName,CLIENT_ROLE_TYPE.CLIENT_ROLE_BROADCASTER, this.RenewOrJoinToken));
            return;
          }

          RtcEngine.JoinChannel(channelToken, channelName, "");
          Debug.Log("joinChannel with token:" + channelToken);
        }

        internal void StartUpdateTokenEveryTenSecond() {
          InvokeRepeating("RequestToken", 10, 10);
        }

        private void RequestToken() {
          StartCoroutine(HelperClass.FetchToken(this.localUid, channelName, CLIENT_ROLE_TYPE.CLIENT_ROLE_BROADCASTER, this.RenewOrJoinToken));
        }

        private void OnDestroy()
        {
          Debug.Log("OnDestroy");
          if (RtcEngine == null) return;
          RtcEngine.InitEventHandler(null);
          RtcEngine.LeaveChannel();
          RtcEngine.Dispose();
        }

        internal string GetChannelName()
        {
          return channelName;
        }

        #region -- Video Render UI Logic ---

        internal static void MakeVideoView(uint uid, string channelId = "")
        {
          GameObject go = GameObject.Find(uid.ToString());
          if (!ReferenceEquals(go, null))
          {
            return;
          }

          VideoSurface videoSurface = MakeImageSurface(uid.ToString());
          if (!ReferenceEquals(videoSurface, null))
          {

            if (uid == 0)
            {
              videoSurface.SetForUser(uid, channelId);
            }
            else
            {
              videoSurface.SetForUser(uid, channelId, VIDEO_SOURCE_TYPE.VIDEO_SOURCE_REMOTE);
            }

            videoSurface.OnTextureSizeModify += (int width, int height) =>
            {
              float scale = (float)height / (float)width;
              videoSurface.transform.localScale = new Vector3(-5, 5 * scale, 1);
              Debug.Log("OnTextureSizeModify: " + width + " " + height);
            };

            videoSurface.SetEnable(true);
          }
        }

        private static VideoSurface MakePlaneSurface(string goName)
        {
          GameObject go = GameObject.CreatePrimitive(PrimitiveType.Plane);

          if (go == null)
          {
            return null;
          }

          go.name = goName;

          go.transform.Rotate(-90.0f, 0.0f, 0.0f);
          go.transform.position = Vector3.zero;
          go.transform.localScale = new Vector3(0.25f, 0.5f, .5f);

          var videoSurface = go.AddComponent<VideoSurface>();
          return videoSurface;
        }

        private static VideoSurface MakeImageSurface(string goName)
        {
          GameObject go = new GameObject();

          if (go == null)
          {
            return null;
          }

          go.name = goName;
          go.AddComponent<RawImage>();
          go.AddComponent<UIElementDrag>();
          GameObject canvas = GameObject.Find("VideoCanvas");
          if (canvas != null)
          {
            go.transform.parent = canvas.transform;
            Debug.Log("add video view");
          }
          else
          {
            Debug.Log("Canvas is null video view");
          }

          go.transform.Rotate(0f, 0.0f, 180.0f);
          go.transform.localPosition = Vector3.zero;
          go.transform.localScale = new Vector3(3f, 4f, 1f);

          var videoSurface = go.AddComponent<VideoSurface>();
          return videoSurface;
        }

        internal static void DestroyVideoView(uint uid)
        {
          GameObject go = GameObject.Find(uid.ToString());
          if (!ReferenceEquals(go, null))
          {
            Object.Destroy(go);
          }
        }

        #endregion
      }

      internal class UserEventHandler : IRtcEngineEventHandler
      {
        private readonly JoinChannelVideoToken _helloVideoTokenAgora;

        internal UserEventHandler(JoinChannelVideoToken helloVideoTokenAgora)
        {
          _helloVideoTokenAgora= helloVideoTokenAgora;
        }

        public override void OnError(int err, string msg)
        {
          Debug.Log(string.Format("OnError err: {0}, msg: {1}", err, msg));
        }
        // Joined the channel successfully
        public override void OnJoinChannelSuccess(RtcConnection connection, int elapsed)
        {
          int build = 0;
          Debug.Log(string.Format("sdk version: ${0}",
            _helloVideoTokenAgora.RtcEngine.GetVersion(ref build)));
          Debug.Log(
            string.Format("OnJoinChannelSuccess channelName: {0}, uid: {1}, elapsed: {2}",
              connection.channelId, connection.localUid, elapsed));
          Debug.Log(string.Format("New Token: {0}",
            JoinChannelVideoToken.channelToken));
          JoinChannelVideoToken.MakeVideoView(0);

          _helloVideoTokenAgora.localUid = connection.localUid;
          _helloVideoTokenAgora.StartUpdateTokenEveryTenSecond();
        }

        public override void OnUserJoined(RtcConnection connection, uint uid, int elapsed)
        {
          Debug.Log(string.Format("OnUserJoined uid: ${0} elapsed: ${1}", uid,
            elapsed));
          JoinChannelVideoToken.MakeVideoView(uid, _helloVideoTokenAgora.GetChannelName());
        }

        public override void OnUserOffline(RtcConnection connection, uint uid, USER_OFFLINE_REASON_TYPE reason)
        {
          Debug.Log(string.Format("OnUserOffLine uid: ${0}, reason: ${1}", uid,
            (int)reason));
          JoinChannelVideoToken.DestroyVideoView(uid);
        }
        //The token is about to expire
        public override void OnTokenPrivilegeWillExpire(RtcConnection connection, string token)
        {
          _helloVideoTokenAgora.StartCoroutine(HelperClass.FetchToken(_helloVideoTokenAgora.localUid,
            _helloVideoTokenAgora.GetChannelName(), CLIENT_ROLE_TYPE.CLIENT_ROLE_BROADCASTER, _helloVideoTokenAgora.RenewOrJoinToken));
        }

        public override void OnConnectionStateChanged(RtcConnection connection, CONNECTION_STATE_TYPE state,
          CONNECTION_CHANGED_REASON_TYPE reason)
        {
          _helloVideoTokenAgora._state = state;
        }

        public override void OnConnectionLost(RtcConnection connection)
        {
          Debug.Log(string.Format("OnConnectionLost "));
        }
      }

      #endregion
    }

    namespace Agora.Util
    {
      public static class HelperClass
      {
        public static IEnumerator FetchToken(uint uid, string channelName, CLIENT_ROLE_TYPE role, Action<TokenObject> callback = null)
        {

          Dictionary<string, object> postParams = new Dictionary<string, object>();
          postParams.Add("uid", uid);
          postParams.Add("ChannelName", channelName);
          postParams.Add("role", role);
          string json = AgoraJson.ToJson<Dictionary<string, object>>(postParams);
          var url = "http://127.0.0.1/fetch_rtc_token";

          byte[] postBytes = System.Text.Encoding.Default.GetBytes(json);
          UnityWebRequest request = new UnityWebRequest(url, "POST");

          request.uploadHandler = (UploadHandler)new UploadHandlerRaw(postBytes);
          request.downloadHandler = (DownloadHandler)new DownloadHandlerBuffer();
          request.SetRequestHeader("Content-Type", "application/json");
          yield return request.SendWebRequest();

          if (request.isNetworkError || request.isHttpError)
          {
            Debug.Log(request.error);
            callback(null);
            yield break;
          }
          Debug.Log("text: " + request.downloadHandler.text);
          TokenObject tokenInfo = JsonUtility.FromJson<TokenObject>(request.downloadHandler.text);
          callback(tokenInfo);
        }
      }
    }
```

Replace `<Your app ID>` with your app ID, which must be consistent with the app ID you specified in the server configuration. Update `url` with the host URL and port of the local Golang server you have deployed.

The sample code implements the following logic:

* Calls `JoinChannel` to join a channel using the user ID, the channel name, and a token you obtain from the server. The user ID and channel name you specify must be consistent with the values you used to generate the token.

* The SDK triggers an `OnTokenPrivilegeWillExpire` callback 30 seconds before the token expires. After receiving the callback, you obtain a new token from the server and call `RenewToken` to pass the newly generated token to the SDK.

Build and run the project on the local device, the game performs the following operations:

* Obtains a token from your token server.
* Joins the channel.
* Automatically renews the token when it is about to expire.

<CalloutContainer type="info">
  <CalloutDescription>
    The user ID and channel name used to join a channel must be consistent with the values used to generate the token.
  </CalloutDescription>
</CalloutContainer>

## Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.