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

> 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 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

The client requests a token from your authentication server corresponding to the user ID and the channel name. You use the received token to join a channel.

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  <CodeBlockTab value="java">
    ```java
    // Channel name
    String channelId = "xxx";
    // User ID
    int uid = 0;
    // Request a token from the server corresponding to channelId and uid
    String token = getToken(channelId, uid);
    // Set channel media options
    ChannelMediaOptions option = new ChannelMediaOptions();
    option.clientRoleType = Constants.CLIENT_ROLE_BROADCASTER;
    // Join a channel
    engine.joinChannel(token, channelId, 0, option);
    ```
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  <CodeBlockTab value="kotlin">
    ```kotlin
    // Channel name
    val channelId = "xxx"
    // User ID
    val uid = 0
    // Request a token from the server corresponding to channelId and uid
    val token = getToken(channelId, uid)
    // Set channel media options
    val option = ChannelMediaOptions().apply {
      clientRoleType = Constants.CLIENT_ROLE_BROADCASTER
    }
    // Join a channel
    engine.joinChannel(token, channelId, 0, option)
    ```
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### Token expiration

After you join a channel using a token, the SDK triggers an `onTokenPrivilegeWillExpire` callback, 30 seconds before the token is set to expire.

When the token expires, the SDK triggers an `onRequestToken` callback. After receiving the callback, you regenerate a new token on the server side, and then update the token in one of the following ways:

#### Single channel use-case

* Call `renewToken` to pass in the newly generated Token (Recommended).

* Call `updateChannelMediaOptions` to update the token.

* Call `leaveChannel` \[2/2] to leave the current channel, and then pass in a new token when calling `joinChannel` \[2/2] to rejoin the channel.

#### Multi-channel use-case

If you call `joinChannelEx` to join multiple channels, call the `updateChannelMediaOptionsEx` method to update the token.

The following sample code demonstrates how to call `renewToken` to update the token upon receiving an `onTokenPrivilegeWillExpire` callback notification.

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    ```java
    class RtcEngineEventHandlerImpl extends IRtcEngineEventHandler {
      // Callback is triggered when the token is about to expire
      @Override
      public void onTokenPrivilegeWillExpire(String token) {
        super.onTokenPrivilegeWillExpire(token);

        // Request to generate a fresh token
        String token = getToken();
        // Update token
        engine.renewToken(token);
      }
    }
    ```
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  <CodeBlockTab value="kotlin">
    ```kotlin
    class RtcEngineEventHandlerImpl : IRtcEngineEventHandler() {
      // Callback triggered when the token is about to expire
      override fun onTokenPrivilegeWillExpire(token: String) {
        super.onTokenPrivilegeWillExpire(token)

        // Request to generate a fresh token
        val newToken = getToken()
        // Update the token
        engine.renewToken(newToken)
      }
    }
    ```
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### Complete sample code

This section presents sample code to implement token authentication in your client.

1. In `/Gradle Scripts/build.gradle(Module: <projectname>.app)`, add the following dependencies for making HTTP requests to the token server:

   ```yaml
   dependencies {
    implementation 'com.squareup.okhttp3:okhttp:3.10.0'
    implementation 'com.google.code.gson:gson:2.8.4'
   }
   ```

2. In `MainActivity`, replace the content with the following code:

**Complete sample code for token authentication**

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  <CodeBlockTab value="java">
    ```java
    package com.example.rtcquickstart;
      import androidx.appcompat.app.AppCompatActivity;
      import android.os.Bundle;
      import androidx.core.app.ActivityCompat;
      import androidx.core.content.ContextCompat;

      import android.Manifest;
      import android.content.pm.PackageManager;
      import android.view.SurfaceView;
      import android.widget.FrameLayout;
      import android.widget.Toast;
      import io.agora.rtc2.Constants;
      import io.agora.rtc2.IRtcEngineEventHandler;
      import io.agora.rtc2.RtcEngine;
      import io.agora.rtc2.video.VideoCanvas;
      import io.agora.rtc2.ChannelMediaOptions;

      import okhttp3.MediaType;
      import okhttp3.OkHttpClient;
      import okhttp3.Request;
      import okhttp3.RequestBody;
      import okhttp3.Response;
      import okhttp3.Call;
      import okhttp3.Callback;

      import com.google.gson.Gson;
      import java.util.Map;
      import org.json.JSONException;
      import org.json.JSONObject;
      import java.io.IOException;

      public class MainActivity extends AppCompatActivity {

       // Fill in the App ID from Agora console
       private String appId = "Your App ID";
       // Fill in the channel name
       private String channelName = "demo";
       private String token = "";
       private RtcEngine mRtcEngine;
       private int joined = 1;

       private final IRtcEngineEventHandler mRtcEventHandler = new IRtcEngineEventHandler() {
         @Override
         public void onUserJoined(int uid, int elapsed) {
            runOnUiThread(() -> setupRemoteVideo(uid));
         }

         @Override
         public void onTokenPrivilegeWillExpire(String token) {
            fetchToken(1234, channelName, 1);
            runOnUiThread(() -> {
             Toast toast = Toast.makeText(MainActivity.this, "Token renewed", Toast.LENGTH_SHORT);
             toast.show();
            });
            super.onTokenPrivilegeWillExpire(token);
         }

         @Override
         public void onRequestToken() {
            joined = 1;
            fetchToken(1234, channelName, 1);
            super.onRequestToken();
         }
       };

       private static final int PERMISSION_REQ_ID = 22;

       private static final String[] REQUESTED_PERMISSIONS = {
            Manifest.permission.RECORD_AUDIO,
            Manifest.permission.CAMERA
       };

       private boolean checkSelfPermission(String permission, int requestCode) {
         if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode);
            return false;
         }
         return true;
       }

       // Get RTC Token
       private void fetchToken(int uid, String channelName, int tokenRole) {
         OkHttpClient client = new OkHttpClient();
         MediaType JSON = MediaType.parse("application/json; charset=utf-8");
         JSONObject json = new JSONObject();
         try {
            json.put("uid", uid);
            json.put("ChannelName", channelName);
            json.put("role", tokenRole);
         } catch (JSONException e) {
            e.printStackTrace();
         }

         RequestBody requestBody = RequestBody.create(JSON, String.valueOf(json));
         Request request = new Request.Builder()
             .url("http://<Your Host URL and port>/fetch_rtc_token")
             .header("Content-Type", "application/json; charset=UTF-8")
             .post(requestBody)
             .build();
         Call call = client.newCall(request);
         call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
             if (response.isSuccessful()) {
               Gson gson = new Gson();
               String result = response.body().string();
               Map map = gson.fromJson(result, Map.class);
               new Thread(() -> {
                  token = map.get("token").toString();
                  ChannelMediaOptions options = new ChannelMediaOptions();
                  if (joined != 0) {
                   joined = mRtcEngine.joinChannel(token, channelName, 1234, options);
                  } else {
                   mRtcEngine.renewToken(token);
                  }
               }).start();
             }
            }
         });
       }

       @Override
       protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         if (checkSelfPermission(REQUESTED_PERMISSIONS[0], PERMISSION_REQ_ID) &&
             checkSelfPermission(REQUESTED_PERMISSIONS[1], PERMISSION_REQ_ID)) {
            initializeAndJoinChannel();
         }
       }

       @Override
       protected void onDestroy() {
         super.onDestroy();
         mRtcEngine.leaveChannel();
         mRtcEngine.destroy();
       }

       private void initializeAndJoinChannel() {
         try {
            mRtcEngine = RtcEngine.create(getBaseContext(), appId, mRtcEventHandler);
         } catch (Exception e) {
            throw new RuntimeException("Check the error.");
         }

         mRtcEngine.setChannelProfile(Constants.CHANNEL_PROFILE_LIVE_BROADCASTING);
         mRtcEngine.setClientRole(Constants.CLIENT_ROLE_BROADCASTER);
         mRtcEngine.enableVideo();

         FrameLayout container = findViewById(R.id.local_video_view_container);
         SurfaceView surfaceView = new SurfaceView(getBaseContext());
         container.addView(surfaceView);
         mRtcEngine.setupLocalVideo(new VideoCanvas(surfaceView, VideoCanvas.RENDER_MODE_FIT, 0));
         mRtcEngine.startPreview();
         fetchToken(1234, channelName, 1);
       }

       private void setupRemoteVideo(int uid) {
         FrameLayout container = findViewById(R.id.remote_video_view_container);
         SurfaceView surfaceView = new SurfaceView(getBaseContext());
         surfaceView.setZOrderMediaOverlay(true);
         container.addView(surfaceView);
         mRtcEngine.setupRemoteVideo(new VideoCanvas(surfaceView, VideoCanvas.RENDER_MODE_FIT, uid));
       }
      }
    ```
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  <CodeBlockTab value="kotlin">
    ```kotlin
    package com.example.rtcquickstart

      import android.Manifest;
      import android.content.pm.PackageManager;
      import android.os.Bundle;
      import android.view.SurfaceView;
      import android.widget.FrameLayout;
      import android.widget.Toast;

      import androidx.appcompat.app.AppCompatActivity;
      import androidx.core.app.ActivityCompat;
      import androidx.core.content.ContextCompat;

      import io.agora.rtc2.*;
      import io.agora.rtc2.video.VideoCanvas;

      import com.google.gson.Gson;
      import okhttp3.*;
      import org.json.JSONException;
      import org.json.JSONObject;
      import java.io.IOException;
      import java.util.*;

      class MainActivity : AppCompatActivity() {

       // Fill in the App ID from Agora console
       private val appId = "Your App ID"
       // Fill in the channel name
       private val channelName = "demo"
       private var token = ""
       private var mRtcEngine: RtcEngine? = null
       private var joined = 1

       private val mRtcEventHandler = object : IRtcEngineEventHandler() {
         override fun onUserJoined(uid: Int, elapsed: Int) {
            runOnUiThread {
             // After obtaining the user ID in the onUserJoined callback, call setupRemoteVideo to set the remote user view
             setupRemoteVideo(uid)
            }
         }

         override fun onTokenPrivilegeWillExpire(token: String) {
            fetchToken(1234, channelName, 1)
            runOnUiThread {
             val toast = Toast.makeText(this@MainActivity, "Token renewed", Toast.LENGTH_SHORT)
             toast.show()
            }
            super.onTokenPrivilegeWillExpire(token)
         }

         override fun onRequestToken() {
            joined = 1
            fetchToken(1234, channelName, 1)
            super.onRequestToken()
         }
       }

       companion object {
         private const val PERMISSION_REQ_ID = 22
         private val REQUESTED_PERMISSIONS = arrayOf(
            Manifest.permission.RECORD_AUDIO,
            Manifest.permission.CAMERA
         )
       }

       private fun checkSelfPermission(permission: String, requestCode: Int): Boolean {
         return if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode)
            false
         } else {
            true
         }
       }

       // Get RTC Token
       private fun fetchToken(uid: Int, channelName: String, tokenRole: Int) {
         val client = OkHttpClient()
         val JSON = MediaType.parse("application/json; charset=utf-8")
         val json = JSONObject()
         try {
            json.put("uid", uid)
            json.put("ChannelName", channelName)
            json.put("role", tokenRole)
         } catch (e: JSONException) {
            e.printStackTrace()
         }

         val requestBody = RequestBody.create(JSON, json.toString())
         val request = Request.Builder()
            .url("http://<Your Host URL and port>/fetch_rtc_token")
            .header("Content-Type", "application/json; charset=UTF-8")
            .post(requestBody)
            .build()

         client.newCall(request).enqueue(object : Callback {
            override fun onFailure(call: Call, e: IOException) {
             // Handle failure
            }

            override fun onResponse(call: Call, response: Response) {
             if (response.isSuccessful) {
               val gson = Gson()
               val result = response.body?.string()
               val map: Map<String, Any> = gson.fromJson(result, Map::class.java)
               Thread {
                  token = map["token"].toString()
                  // If the user has not joined the channel, use token to join the channel
                  val options = ChannelMediaOptions()
                  if (joined != 0) {
                   joined = mRtcEngine?.joinChannel(token, channelName, 1234, options) ?: -1
                  } else {
                   mRtcEngine?.renewToken(token)
                  }
               }.start()
             }
            }
         })
       }

       override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)

         // If all permissions are granted, initialize the RtcEngine object and join the channel
         if (checkSelfPermission(REQUESTED_PERMISSIONS[0], PERMISSION_REQ_ID) &&
            checkSelfPermission(REQUESTED_PERMISSIONS[1], PERMISSION_REQ_ID)) {
            initializeAndJoinChannel()
         }
       }

       override fun onDestroy() {
         super.onDestroy()
         mRtcEngine?.leaveChannel()
         mRtcEngine?.destroy()
       }

       private fun initializeAndJoinChannel() {
         try {
            mRtcEngine = RtcEngine.create(baseContext, appId, mRtcEventHandler)
         } catch (e: Exception) {
            throw RuntimeException("Check the error.")
         }

         // In interactive live broadcast, set the channel scene to BROADCASTING
         mRtcEngine?.setChannelProfile(Constants.CHANNEL_PROFILE_LIVE_BROADCASTING)
         // Depending on the actual situation, set the user role to BROADCASTER or AUDIENCE
         mRtcEngine?.setClientRole(Constants.CLIENT_ROLE_BROADCASTER)

         // SDK turns off video by default. Call enableVideo to enable video
         mRtcEngine?.enableVideo()

         val container: FrameLayout = findViewById(R.id.local_video_view_container)
         // Call CreateRendererView to create a SurfaceView object and add it as a child to the FrameLayout
         val surfaceView = SurfaceView(baseContext)
         container.addView(surfaceView)
         // Pass the SurfaceView object to Agora to render local video
         mRtcEngine?.setupLocalVideo(VideoCanvas(surfaceView, VideoCanvas.RENDER_MODE_FIT, 0))
         // Start local video preview
         mRtcEngine?.startPreview()
         // Get a token from the token server
         fetchToken(1234, channelName, 1)
       }

       private fun setupRemoteVideo(uid: Int) {
         val container: FrameLayout = findViewById(R.id.remote_video_view_container)
         val surfaceView = SurfaceView(baseContext)
         surfaceView.setZOrderMediaOverlay(true)
         container.addView(surfaceView)
         mRtcEngine?.setupRemoteVideo(VideoCanvas(surfaceView, VideoCanvas.RENDER_MODE_FIT, uid))
       }
      }
    ```
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<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.

### API reference

* [`joinChannel` \[2/2\]](https://api-ref.agora.io/en/video-sdk/android/4.x/API/class_irtcengine.html#api_irtcengine_joinchannel2)

* [`renewToken`](https://api-ref.agora.io/en/video-sdk/android/4.x/API/class_irtcengine.html#api_irtcengine_renewtoken)

* [`onTokenPrivilegeWillExpire`](https://api-ref.agora.io/en/video-sdk/android/4.x/API/class_irtcengineeventhandler.html#callback_irtcengineeventhandler_ontokenprivilegewillexpire)