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Authentication
Learn how to add authentication to a content extension.
If an authentication-enabled app has a content extension, users of the app must authenticate with a third-party platform before they can access the app's content.
This topic explains how to implement authentication in a content extension.
Step 1: Enable authentication
By default, authentication is disabled.
To enable authentication:
- 1.
- 2.Click Authentication.
- 3.Enable This app requires authentication.
The Authentication page has two fields:
- Redirect URL
- Authentication base URL
The purpose of these fields is explained in the following steps.
Step 2: Check if the user is authenticated
When a user opens a content extension, Canva sends a
POST request to the following endpoint:1
<base_url>/content/resources/find
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The body of this request includes a
user property that contains the ID of the user. Your extension can use this ID to check if the current user is associated with a user in the backend of a third-party platform.If the ID of the Canva user is not associated with a user of the third-party platform, respond to the request with the following object:
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{
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"type": "ERROR",
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"errorCode": "CONFIGURATION_REQUIRED"
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}
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This tells Canva to render a Connect button. Users can select the button to begin the authentication flow.
The user's ID is obfuscated and unique to each app. If an app has multiple extensions, each extension will receive the same ID for a user, but different apps will receive different IDs for the same user.
If the ID of the Canva user is associated with a user of the third-party platform, respond with the content that Canva should render in the side panel:
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{
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"type": "SUCCESS",
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"resources": []
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}
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Typically, this content will belong to the authenticated user.
Canva includes the ID of the user's team in all requests, via the
brand property. You can use this ID to add team-specific features to an extension.Step 3: Redirect users to the Redirect URL
When a user clicks the Connect button, Canva opens a pop-up window.
Inside this window, Canva redirects the user to the app's Redirect URL.
The Redirect URL must point to a page that lets users authenticate with the third-party platform. For example, this could be a login form with a username and password, or the start of an OAuth 2.0 authorization flow. The exact authentication method is the responsibility of the app. Canva doesn't enforce any specific approach.
When redirecting users to the Redirect URL, Canva automatically appends a number of query parameters to the URL. All of these parameters serve a purpose, but the
user and state parameters are of particular importance.The
user parameter contains the ID of the user. If the user successfully authenticates, the app needs to persist this ID to a datastore. When the user returns to the app, the app can use this ID to check if the user is authenticated or not.The
state parameter contains a unique token for the authentication flow. For security reasons, the app must return this token to Canva at the end of the authentication flow. This protects the app against cross-site request forgery (CSRF) attacks.Step 4: Verify the request signature
The redirection from Canva to the Redirect URL is a
GET request. Before you can submit an app for review, you must implement signature verification for this request. This prevents third-parties from sending requests to the URL.Step 5: Redirect the user back to Canva
At the end of the authentication flow, redirect users to the following URL from within the pop-up window:
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https://canva.com/apps/configured?success=<true|false>&state=<token>
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This must be a
302 redirect.You also need to append the following parameters to the URL:
successstate
If the user has successfully authenticated, set the
success parameter to true. This tells Canva to close the pop-up window and reload the extension. When the extension reloads, it can once again check if the user is authenticated.If the user has not successfully authenticated, set the
success parameter to false. This tells Canva to close the pop-up window without reloading the extension.Always set the
state parameter to the value of the token that Canva provided at the start of the authentication flow. If the state parameter is missing or invalid, an error occurs and the authentication fails.Canva's
state parameter is distinct from OAuth 2.0's state parameter.Step 6: Let users disconnect from Canva
After a user authenticates, they have the option of revoking that authentication. Your app must support this option to be eligible for distribution via the Apps Directory.
When a user disconnects an app, Canva sends a
POST request to the following endpoint:1
<authentication_base_url>/configuration/delete
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<authentication_base_url> is a placeholder that refers to the app's Authentication base URL field, which can be set via the Authentication page in the Developer Portal.Canva automatically appends the
/configuration/delete path to the URL. Don't include the path in the Authentication base URL field.The body of this request includes a
user property, which contains the ID of the user. Your app can use this ID to remove the association between the Canva user and the user in the backend of the third-party platform.Example
This example uses ESM modules, which means it uses the
import keyword instead of the require keyword. To run the example, add 'type': 'module' to the package.json file.1
import basicAuth from "express-basic-auth";
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import express from "express";
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import querystring from "querystring";
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import { Low, JSONFile } from "lowdb";
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​
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const app = express();
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​
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app.use(express.json());
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app.use(express.static("public"));
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​
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// Set up the database
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// Docs: https://github.com/typicode/lowdb
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const adapter = new JSONFile("db.json");
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const db = new Low(adapter);
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await db.read();
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db.data ||= { loggedInUsers: [] };
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​
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// Set up Redirect URL
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app.get(
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"/login",
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basicAuth({
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users: { admin: "password123" },
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challenge: true,
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}),
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async (request, response) => {
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const { loggedInUsers } = db.data;
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const { user } = request.query;
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​
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// Add the user to the database
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if (!loggedInUsers.includes(user)) {
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loggedInUsers.push(user);
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await db.write();
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}
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​
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// Construct query parameters for redirect back to Canva
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const params = querystring.stringify({
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success: true,
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state: request.query.state,
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});
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​
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// Redirect back to Canva
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response.redirect(302, `https://canva.com/apps/configured?${params}`);
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}
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);
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​
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// Handle requests for content
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app.post("/content/resources/find", async (request, response) => {
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const { loggedInUsers } = db.data;
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const { user } = request.body;
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​
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// The user is logged-in
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if (loggedInUsers.includes(user)) {
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response.send({
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type: "SUCCESS",
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resources: [
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{
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type: "IMAGE",
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id: "123456",
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name: "Leaning Tower of Pisa",
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thumbnail: {
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url: "https://picsum.photos/id/629/600",
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},
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url: "https://picsum.photos/id/629/2000",
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contentType: "image/jpeg",
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},
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],
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});
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return;
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}
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​
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// The user is not logged-in
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response.send({
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type: "ERROR",
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errorCode: "CONFIGURATION_REQUIRED",
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});
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});
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​
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// Handle disconnection requests
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app.post("/configuration/delete", async (request, response) => {
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// Remove the current user from the database
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db.data.loggedInUsers = db.data.loggedInUsers.filter((user) => {
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return user !== request.body.user;
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});
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await db.write();
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​
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response.send({
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type: "SUCCESS",
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});
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});
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​
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app.listen(process.env.PORT || 3000);
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Last modified 2mo ago