# Use tokens (/en/realtime-media/broadcast-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 [#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 Broadcast Streaming:

    **Token authentication flow**

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

    ## Prerequisites [#prerequisites-9]

    Before starting, ensure that you have:

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

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

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

    ## Implement basic authentication [#implement-basic-authentication-9]

    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 [#use-a-token-to-join-a-channel-8]

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

    1. Open the [SDK quickstart](../../index) 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 [#reference-9]

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