VK ID

Pure dart impl of OAuth VK ID API. The module allows to generate 'authorize' link, retrieve OAuth token and user data

General

• Dart SDK >=3.3.0

Supports 2 modes:

• Front-end authorization code exchange without SDK: Generating random code_verifier and state at front-end
• Back-end authorization code exchange without SDK: Generating random code_verifier and state at back-end and sending code_challenge with state to front-end

Supports VK app platforms:

• Android
• iOS
• Web

Notice: You aren't strictly bound between the hardware and the VK app platform. For example, you can authorize on iOS VK app using Android device

Supports VK ID APIs:

• Generating 'auhtorize' link for VK ID with code_verifier or code_challenge
• Exchange received from passed user login redirect authorization code for access, refresh, id tokens
• Refresh access token through refresh token
• Get public (masked) user info
• Get full (unmasked) user info
• Revoke permissions for authorization
• Invalidate authorization (Logout)

Notice: This module doesn't support user authorization. Use webview on flutter context to do it

Setup

1. Create and setup VK app
2. Create VkIDController instance with VK app client ID

If you have previously saved authorization, you can set init oauth and profile data for controller ctor

Authorization

Generating authorize link

You may generate authorize link itself (redirect_uri and code_challenge or code_verifier) or request the generated link from back-end

• Android, iOS: Redirect uri must be 'vk{clientID}://vk.com/blank.html'. Otherwise VK will throw an error for authorize
• Web: Redirect uri must match with uri from VK web app settings. Also you can use default value from Android and iOS apps (vk{clientID}://vk.com/blank.html)

Authorize link generation examples

1. Android and iOS with code_challenge

final controller = VkIDController(clID: 1234567890);
//Generate code_verifier and code_challenge itself or get code_challenge from back-end
final codeChallenge = "1234567890RND0987654321";
final uri = controller.generateAuthorizeLinkWithCodeChallenge(codeChallenge: codeChallenge);

2. Android and iOS with random code_verifier

final controller = VkIDController(clID: 1234567890);
final codeVerifierWithUri = controller.generateAuthorizeLinkWithCodeVerifier();

3. Android and iOS with user-defined code_verifier

final controller = VkIDController(clID: 1234567890);
//Generate code_verifier
final codeVerifier = "1234567890RND0987654321";
final codeVerifierWithUri = controller.generateAuthorizeLinkWithCodeVerifier(codeVerifier: codeVerifier);

4. Web with code_challenge and user-defined redirect_uri from VK web app settings

final controller = VkIDController(clID: 1234567890);
final redirectUri = "https://site.com/redirect";
//Generate code_verifier and code_challenge itself or get code_challenge from back-end
final codeChallenge = "1234567890RND0987654321";
final uri = controller.generateAuthorizeLinkWithCodeChallenge(codeChallenge: codeChallenge, redirectUri: redirectUri);

5. Web with code_challenge and default redirect_uri

final controller = VkIDController(clID: 1234567890);
//Generate code_verifier and code_challenge itself or get code_challenge from back-end
final codeChallenge = "1234567890RND0987654321";
final uri = controller.generateAuthorizeLinkWithCodeChallenge(codeChallenge: codeChallenge);

6. Web with random code_verifier and user-defined redirect_uri from VK web app settings

final controller = VkIDController(clID: 1234567890);
final redirectUri = "https://site.com/redirect";
//Generate code_verifier
final codeVerifier = "1234567890RND0987654321";
final codeVerifierWithUri = controller.generateAuthorizeLinkWithCodeVerifier(codeVerifier: codeVerifier);

7. Web with random code_verifier and default redirect_uri

final controller = VkIDController(clID: 1234567890);
//Generate code_verifier
final codeVerifier = "1234567890RND0987654321";
final codeVerifierWithUri = controller.generateAuthorizeLinkWithCodeVerifier(codeVerifier: codeVerifier);

Authorizing on VK ID

You need flutter context and webview to handle it

Pass authorize link to webview. Also include NavigationDelegate for preventing redirect navigation requests. See example for details On success authorization you will be redirected by uri from redirect_uri + query parameters

• Front-end mode: Block redirect from id.vk.com on webview context (Prevent navigation request). Also you need extract 'code' and 'device_id' parameters from query for exchanging OAuth token
• Back-end mode: If VK app is web, don't block redirect. Otherwise block it and process authorization data

Retrieve OAuth token

• Front-end mode: Use controller method to exchange authorization_code for access_token
• Back-end mode: Send, if needed, data to back-end for exchanging

VK ID controller refreshes the access token itself if necessary