# Use tokens (/en/realtime-media/rtc/build/authenticate-users/authentication-workflow/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 app retrieves a token from the token server in your security infrastructure. Your app 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 Video Calling:

<Accordions>
  <Accordion title="Token authentication flow">
    ![token authentication flow](https://assets-docs.agora.io/images/video-sdk/token-authentication.svg)
  </Accordion>
</Accordions>

## Prerequisites

Before starting, ensure that you have:

* Implemented the [Quickstart](/en/realtime-media/rtc/get-started-sdk) in your project.

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

  * [Deploy a token server](/en/realtime-media/rtc/build/authenticate-users/deploy-token-server)
  * [Deploy a middleware server](/en/realtime-media/rtc/build/authenticate-users/middleware-token-server)

## 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 app.

1. Open the [SDK quickstart](/en/realtime-media/rtc/get-started-sdk) 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 app 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="warning">
  <CalloutTitle>
    Note
  </CalloutTitle>

  <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.