Penautan Akun Google dengan OAuth

Akun ditautkan menggunakan alur implisit dan kode otorisasi OAuth 2.0 standar industri. Layanan Anda harus mendukung endpoint otorisasi dan pertukaran token yang mematuhi OAuth 2.0.

Dalam alur implisit, Google akan membuka endpoint otorisasi Anda di browser pengguna. Setelah berhasil login, Anda akan menampilkan token akses dengan masa berlaku lama ke Google. Token akses ini kini disertakan dalam setiap permintaan yang dikirim dari Google.

Dalam alur kode otorisasi, Anda memerlukan dua endpoint:

• Endpoint Authorization, yang menampilkan UI login kepada pengguna Anda yang belum login. Endpoint otorisasi juga membuat kode otorisasi berumur pendek untuk mencatat izin pengguna ke akses yang diminta.

• Endpoint pertukaran token, yang bertanggung jawab atas dua jenis pertukaran:

  1. Menukar kode otorisasi dengan token refresh yang berumur panjang dan token akses yang berumur singkat. Pertukaran ini terjadi saat pengguna melalui alur penautan akun.
  2. Menukar token refresh yang memiliki masa aktif lama dengan token akses yang memiliki masa aktif singkat. Pertukaran ini terjadi saat Google memerlukan token akses baru karena token yang ada sudah tidak berlaku lagi.

Pilih alur OAuth 2.0

Meskipun alur implisit lebih mudah diterapkan, Google merekomendasikan agar token akses yang dikeluarkan oleh alur implisit tidak pernah berakhir masa berlakunya. Hal ini karena pengguna dipaksa untuk menautkan akunnya lagi setelah token berakhir masa berlakunya dengan alur implisit. Jika Anda memerlukan masa berlaku token karena alasan keamanan, sebaiknya gunakan alur kode otorisasi.

Catatan: Gunakan tombol berikut untuk memilih alur OAuth 2.0 yang ingin Anda implementasikan. Jika diperlukan, konten panduan ini akan dimuat ulang agar sesuai dengan pilihan Anda.

Alur implisit Kode otorisasi

Panduan desain

Bagian ini menjelaskan persyaratan dan rekomendasi desain untuk layar pengguna yang Anda host untuk alur penautan OAuth. Setelah dipanggil oleh aplikasi Google, platform Anda akan menampilkan halaman login ke Google dan layar izin penautan akun ke pengguna. Pengguna akan diarahkan kembali ke aplikasi Google setelah memberikan izin untuk menautkan akun.

Gambar 1. Akun yang menautkan pengguna, login ke Google dan layar izin.

Persyaratan

1. Anda harus menyampaikan bahwa akun pengguna akan ditautkan ke Google, bukan produk Google tertentu seperti Google Home atau Asisten Google.

Rekomendasi

Sebaiknya Anda melakukan hal berikut:

1. Menampilkan Kebijakan Privasi Google. Sertakan link ke Kebijakan Privasi Google di layar izin.

2. Data yang akan dibagikan. Gunakan bahasa yang jelas dan ringkas untuk memberi tahu pengguna data apa saja yang diperlukan Google dan alasannya.

3. Pesan ajakan (CTA) yang jelas. Nyatakan pesan ajakan yang jelas di layar izin, seperti “Setuju dan tautkan”. Hal ini karena pengguna perlu memahami data apa yang harus mereka bagikan kepada Google untuk menautkan akun mereka.

4. Kemampuan untuk membatalkan. Berikan cara bagi pengguna untuk kembali atau membatalkan, jika mereka memilih untuk tidak menautkan.

5. Proses login yang jelas. Pastikan pengguna memiliki metode yang jelas untuk login ke Akun Google mereka, seperti kolom untuk nama pengguna dan sandi mereka atau Login dengan Google.

6. Kemampuan untuk membatalkan tautan. Tawarkan mekanisme bagi pengguna untuk membatalkan tautan, seperti URL ke setelan akun mereka di platform Anda. Atau, Anda dapat menyertakan link ke Akun Google tempat pengguna dapat mengelola akun tertaut mereka.

7. Kemampuan untuk mengubah akun pengguna. Sarankan metode bagi pengguna untuk beralih akun. Hal ini sangat bermanfaat jika pengguna cenderung memiliki beberapa akun.

   • Jika pengguna harus menutup layar izin untuk beralih akun, kirim error yang dapat dipulihkan ke Google sehingga pengguna dapat login ke akun yang diinginkan dengan penautan OAuth dan alur implisit.

8. Sertakan logo Anda. Menampilkan logo perusahaan Anda di layar izin. Gunakan panduan gaya untuk menempatkan logo. Jika Anda juga ingin menampilkan logo Google, lihat Logo dan merek dagang.

Gambar 2. Panduan desain untuk login pengguna ke Google dan layar izin.

Create the project

Note: You can reuse an existing project and do not need to create a new project primarily for account linking.

To create your project to use account linking:

1. Go to the Google API Console.
2. Click Create project.
3. Enter a name or accept the generated suggestion.
4. Confirm or edit any remaining fields.
5. Click Create.

To view your project ID:

1. Go to the Google API Console.
2. Find your project in the table on the landing page. The project ID appears in the ID column.

Configure your OAuth Consent Screen

The Google Account Linking process includes a consent screen which tells users the application requesting access to their data, what kind of data they are asking for and the terms that apply. You will need to configure your OAuth consent screen before generating a Google API client ID.

1. Open the OAuth consent screen page of the Google APIs console.
2. If prompted, select the project you just created.

3. On the "OAuth consent screen" page, fill out the form and click the “Save” button.

   Application name: The name of the application asking for consent. The name should accurately reflect your application and be consistent with the application name users see elsewhere. The application name will be shown on the Account Linking consent screen.

   Application logo: An image on the consent screen that will help users recognize your app. The logo is shown on Account linking consent screen and on account settings

   Support email: For users to contact you with questions about their consent.

   Scopes for Google APIs: Scopes allow your application to access your user's private Google data. For the Google Account Linking use case, default scope (email, profile, openid) is sufficient, you don’t need to add any sensitive scopes. It is generally a best practice to request scopes incrementally, at the time access is required, rather than up front. Learn more.

   Authorized domains: To protect you and your users, Google only allows applications that authenticate using OAuth to use Authorized Domains. Your applications' links must be hosted on Authorized Domains. Learn more.

   Application Homepage link: Home page for your application. Must be hosted on an Authorized Domain.

   Application Privacy Policy link: Shown on Google Account Linking consent screen. Must be hosted on an Authorized Domain.

   Application Terms of Service link (Optional): Must be hosted on an Authorized Domain.

   

   Figure 1. Google Account Linking Consent Screen for a fictitious Application, Tunery

4. Check "Verification Status", if your application needs verification then click the "Submit For Verification" button to submit your application for verification. Refer to OAuth verification requirements for details.

Menerapkan server OAuth

To support the OAuth 2.0 implicit flow, your service makes an authorization endpoint available by HTTPS. This endpoint is responsible for authentication and obtaining consent from users for data access. The authorization endpoint presents a sign-in UI to your users that aren't already signed in and records consent to the requested access.

When a Google application needs to call one of your service's authorized APIs, Google uses this endpoint to get permission from your users to call these APIs on their behalf.

A typical OAuth 2.0 implicit flow session initiated by Google has the following flow:

1. Google opens your authorization endpoint in the user's browser. The user signs in, if not signed in already, and grants Google permission to access their data with your API, if they haven't already granted permission.
2. Your service creates an access token and returns it to Google. To do so, redirect the user's browser back to Google with the access token attached to the request.
3. Google calls your service's APIs and attaches the access token with each request. Your service verifies that the access token grants Google authorization to access the API and then completes the API call.

Handle authorization requests

When a Google application needs to perform account linking via an OAuth 2.0 implicit flow, Google sends the user to your authorization endpoint with a request that includes the following parameters:

Authorization endpoint parameters
client_id	The client ID you assigned to Google.
redirect_uri	The URL to which you send the response to this request.
state	A bookkeeping value that is passed back to Google unchanged in the redirect URI.
response_type	The type of value to return in the response. For the OAuth 2.0 implicit flow, the response type is always token.
user_locale	The Google Account language setting in RFC5646 format used to localize your content in the user's preferred language.

For example, if your authorization endpoint is available at https://myservice.example.com/auth, a request might look like the following:

GET https://myservice.example.com/auth?client_id=GOOGLE_CLIENT_ID&redirect_uri=REDIRECT_URI&state=STATE_STRING&response_type=token&user_locale=LOCALE

For your authorization endpoint to handle sign-in requests, do the following steps:

1. Verify the client_id and redirect_uri values to prevent granting access to unintended or misconfigured client apps:

   • Confirm that the client_id matches the client ID you assigned to Google.
   • Confirm that the URL specified by the redirect_uri parameter has the following form:

     https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID
     https://oauth-redirect-sandbox.googleusercontent.com/r/YOUR_PROJECT_ID
     

2. Check if the user is signed in to your service. If the user isn't signed in, complete your service's sign-in or sign-up flow.

3. Generate an access token for Google to use to access your API. The access token can be any string value, but it must uniquely represent the user and the client the token is for and must not be guessable.

4. Send an HTTP response that redirects the user's browser to the URL specified by the redirect_uri parameter. Include all of the following parameters in the URL fragment:

   • access_token: The access token you just generated
   • token_type: The string bearer
   • state: The unmodified state value from the original request

   The following is an example of the resulting URL:

   https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID#access_token=ACCESS_TOKEN&token_type=bearer&state=STATE_STRING

Google's OAuth 2.0 redirect handler receives the access token and confirms that the state value hasn't changed. After Google has obtained an access token for your service, Google attaches the token to subsequent calls to your service APIs.

Handle userinfo requests

The userinfo endpoint is an OAuth 2.0 protected resource that return claims about the linked user. Implementing and hosting the userinfo endpoint is optional, except for the following use cases:

• Linked Account Sign-In with Google One Tap.
• Frictionless subscription on AndroidTV.

After the access token has been successfully retrieved from your token endpoint, Google sends a request to your userinfo endpoint to retrieve basic profile information about the linked user.

userinfo endpoint request headers
Authorization header	The access token of type Bearer.

For example, if your userinfo endpoint is available at https://myservice.example.com/userinfo, a request might look like the following:

GET /userinfo HTTP/1.1
Host: myservice.example.com
Authorization: Bearer ACCESS_TOKEN

For your userinfo endpoint to handle requests, do the following steps:

1. Extract access token from the Authorization header and return information for the user associated with the access token.
2. If the access token is invalid, return an HTTP 401 Unauthorized error with using the WWW-Authenticate Response Header. Below is an example of a userinfo error response:

   HTTP/1.1 401 Unauthorized
   WWW-Authenticate: error="invalid_token",
   error_description="The Access Token expired"
   

   If a 401 Unauthorized, or any other unsuccessful error response is returned during the linking process, the error will be non-recoverable, the retrieved token will be discarded and the user will have to initiate the linking process again.

3. If the access token is valid, return and HTTP 200 response with the following JSON object in the body of the HTTPS response:

   {
   "sub": "USER_UUID",
   "email": "EMAIL_ADDRESS",
   "given_name": "FIRST_NAME",
   "family_name": "LAST_NAME",
   "name": "FULL_NAME",
   "picture": "PROFILE_PICTURE",
   }

   If your userinfo endpoint returns an HTTP 200 success response, the retrieved token and claims are registered against the user's Google account.

   userinfo endpoint response
   sub	A unique ID that identifies the user in your system.
   email	Email address of the user.
   given_name	Optional: First name of the user.
   family_name	Optional: Last name of the user.
   name	Optional: Full name of the user.
   picture	Optional: Profile picture of the user.

Memvalidasi implementasi

You can validate your implementation by using the OAuth 2.0 Playground tool.

In the tool, do the following steps:

1. Click Configuration to open the OAuth 2.0 Configuration window.
2. In the OAuth flow field, select Client-side.
3. In the OAuth Endpoints field, select Custom.
4. Specify your OAuth 2.0 endpoint and the client ID you assigned to Google in the corresponding fields.
5. In the Step 1 section, don't select any Google scopes. Instead, leave this field blank or type a scope valid for your server (or an arbitrary string if you don't use OAuth scopes). When you're done, click Authorize APIs.
6. In the Step 2 and Step 3 sections, go through the OAuth 2.0 flow and verify that each step works as intended.

You can validate your implementation by using the Google Account Linking Demo tool.

In the tool, do the following steps:

1. Click the Sign-in with Google button.
2. Choose the account you'd like to link.
3. Enter the service ID.
4. Optionally enter one or more scopes that you will request access for.
5. Click Start Demo.
6. When prompted, confirm that you may consent and deny the linking request.
7. Confirm that you are redirected to your platform.