OAuth2 & OpenID Connect Deep Dive · レッスン

OIDCを使用したAuthorization Code Flow

安全なAuthorization Code FlowにOIDCを組み込み、Access TokenとともにID Tokenを返す仕組みを実装します。

「OIDCを使用したAuthorization Code Flow」はCoddyKit上の無料OAuth2 & OpenID Connect Deep Diveレッスンです。これはレッスン1/4です。下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。これはOAuth2 & OpenID Connect Deep Dive学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 OAuth2 & OpenID Connect Deep Diveコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

OIDC & Auth Code Flow Intro

Welcome! In this lesson, we'll combine the secure Authorization Code Flow from OAuth2 with OpenID Connect (OIDC). This allows an application to not only get permission to access resources (OAuth2) but also to verify the user's identity (OIDC).

Think of it as getting both a key to a safe and a valid ID card for the person holding the key, all in one go!

Requesting Identity with OIDC

When using the Authorization Code Flow with OIDC, your application (the Client) starts by sending an authorization request to the Authorization Server. This request is similar to OAuth2 but includes specific OIDC parameters.

response_type=code: Specifies we want an Authorization Code.
scope=openid ...: Crucially, includes the openid scope to signal an OIDC request.
nonce: A unique string to prevent replay attacks (optional but recommended).

The Essential `openid` Scope

The openid scope is the magic flag that tells the Authorization Server you're performing an OpenID Connect request, not just a plain OAuth2 request.

Without openid in your request's scope, the Authorization Server will treat it as a standard OAuth2 flow and will not issue an ID Token.

You can combine openid with other standard OAuth2 scopes like profile, email, or custom scopes.

Beyond `openid`: More Scopes

While openid is mandatory, other OIDC-specific scopes allow you to request more user information:

profile: Access to default profile claims (name, family name, gender, picture, etc.).
email: Access to the user's email address and verification status.
address: Access to the user's postal address.
phone: Access to the user's phone number and verification status.

These claims are then included in the ID Token or accessible via the UserInfo Endpoint.

User Consent & Code Grant

After your app sends the authorization request, the user is redirected to the Authorization Server. They log in (if needed) and are prompted to consent to your app's requested scopes.

If the user approves, the Authorization Server redirects the user back to your app's registered redirect URI, including the Authorization Code in the URL query parameters.

The Token Exchange

Now, your application (running on a server, for confidential clients) takes the received Authorization Code and exchanges it directly with the Authorization Server's token endpoint.

This is a back-channel request, meaning it happens directly between your server and the Authorization Server, not through the user's browser.

Crucially, this exchange now returns three important pieces of information:

Access Token
Refresh Token (if requested)
ID Token

What is the ID Token?

The ID Token is a JSON Web Token (JWT) that contains claims about the authenticated user. It's signed by the Authorization Server, allowing your application to verify its authenticity.

Unlike the Access Token (which is for resource access), the ID Token is specifically for identity verification. It tells your application *who* the user is, not *what* they can do.

ID Token for Identity, Access Token for API

Once your application receives the tokens:

ID Token: You can decode and validate the ID Token to confirm the user's identity and retrieve basic profile information (claims). This is often used for user login sessions.
Access Token: This token is then used to make requests to protected Resource Servers (APIs) on behalf of the user, granting access to specific resources based on the requested scopes.

OIDC Auth Code Flow in Action

Here's a simplified conceptual look at the server-side token exchange. In a real application, you'd use an OIDC client library.

public class OidcClientExample {
  public static void main(String[] args) {
    // 1. User is redirected to Auth Server
    //    Example URL:
    //    https://auth.example.com/oauth/authorize?
    //      response_type=code&
    //      client_id=my_app_id&
    //      scope=openid%20profile%20email&
    //      redirect_uri=https://my-app.com/callback&
    //      nonce=random_string
    
    // 2. User grants consent, redirected back with code
    String authCode = "some_long_authorization_code"; // From redirect URI
    
    // 3. Exchange code for tokens (server-side POST request)
    System.out.println("Exchanging Authorization Code for tokens...");
    // This part would typically be handled by an HTTP client
    // sending a POST request to the token endpoint.
    // The response would contain:
    // {
    //   "access_token": "...",
    //   "token_type": "Bearer",
    //   "expires_in": 3600,
    //   "refresh_token": "...",
    //   "id_token": "..." // The OIDC addition!
    // }
    System.out.println("Received Access Token, Refresh Token, and ID Token!");
    System.out.println("ID Token contains user identity claims.");
  }
}

OIDC Auth Code Flow Check

Consider an application implementing the OpenID Connect Authorization Code Flow.

Which of the following parameters is essential in the initial authorization request to ensure an ID Token is returned?

OIDC Auth Code Flow Recap

Great job! You've learned how the secure Authorization Code Flow is extended by OpenID Connect to provide both authorization and identity.

We use response_type=code and include the openid scope.
The Authorization Server returns an Authorization Code.
This code is exchanged for an Access Token (for resource access) and an ID Token (for user identity).
The ID Token is a JWT carrying user claims, signed by the Authorization Server.

This flow is highly recommended for confidential clients like web applications.

よくある質問

「OIDCを使用したAuthorization Code Flow」レッスンは無料ですか？

はい。「OIDCを使用したAuthorization Code Flow」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、OAuth2 & OpenID Connect Deep Diveコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 OAuth2 & OpenID Connect Deep Diveコースには全4レッスンが含まれています。

「OIDCを使用したAuthorization Code Flow」で何を学びますか？

安全なAuthorization Code FlowにOIDCを組み込み、Access TokenとともにID Tokenを返す仕組みを実装します。ブラウザで直接実行するハンズオンコードでOAuth2 & OpenID Connect Deep Diveを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

OAuth2 & OpenID Connect Deep Diveを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのOAuth2 & OpenID Connect Deep Diveは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。これはレッスン1/4です。

「OIDCを使用したAuthorization Code Flow」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このOAuth2 & OpenID Connect Deep Diveレッスンでコードを書いて実行できますか？

はい。すべてのOAuth2 & OpenID Connect Deep Diveレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

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