# Use tokens (/en/realtime-media/voice/build/set-up-token-authentication/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 Voice Calling:

    **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.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 [#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.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 [#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.