Penautan yang Disederhanakan dengan OAuth dan Login dengan Google

Ringkasan

Penautan yang Disederhanakan Login dengan Google berbasis OAuth menambahkan Login dengan Google di atas penautan OAuth. Hal ini memberikan pengalaman penautan yang lancar bagi pengguna Google, dan juga memungkinkan pembuatan akun, yang memungkinkan pengguna membuat akun baru di layanan Anda menggunakan Akun Google mereka.

Untuk melakukan penautan akun dengan OAuth dan Login dengan Google, ikuti langkah-langkah umum berikut:

1. Pertama, minta pengguna untuk memberikan izin guna mengakses profil Google-nya.
2. Gunakan informasi di profilnya untuk memeriksa apakah akun pengguna tersebut ada.
3. Untuk pengguna lama, tautkan akun.
4. Jika Anda tidak dapat menemukan kecocokan untuk pengguna Google di sistem autentikasi, validasi token ID yang diterima dari Google. Kemudian, Anda dapat membuat pengguna berdasarkan informasi profil yang terdapat dalam token ID.

Gambar 1. Penautan Akun di ponsel pengguna dengan Penautan yang Disederhanakan

Persyaratan untuk Penautan yang Disederhanakan

• Terapkan alur penautan OAuth web dasar. Layanan Anda harus mendukung endpoint otorisasi dan pertukaran token yang sesuai dengan OAuth 2.0.
• Endpoint pertukaran token Anda harus mendukung pernyataan JSON Web Token (JWT) dan menerapkan intent check, create, dan get.

• Mendaftarkan Client ID Google API.

Menerapkan server OAuth

Endpoint pertukaran token Anda harus mendukung intent check, create, get. Gambar di bawah menunjukkan langkah-langkah yang diselesaikan melalui alur penautan akun dan menunjukkan kapan berbagai intent dipanggil:

1. Apakah pengguna memiliki akun di sistem autentikasi Anda? (Pengguna memutuskan dengan memilih YA atau TIDAK)
   1. YA : Apakah pengguna menggunakan email yang terkait dengan Akun Google-nya untuk login ke platform Anda? (Pengguna memutuskan dengan memilih YA atau TIDAK)
      1. YA : Apakah pengguna memiliki akun yang cocok di sistem autentikasi Anda? (check intent dipanggil untuk mengonfirmasi)
         1. YA : get intent dipanggil dan akun ditautkan jika intent get berhasil ditampilkan.
         2. TIDAK : Buat Akun Baru? (Pengguna memutuskan dengan memilih YA atau TIDAK)
            1. YA : create intent dipanggil dan akun ditautkan jika intent pembuatan berhasil ditampilkan.
            2. TIDAK : Alur OAuth Web dipicu, pengguna diarahkan ke browser mereka, dan pengguna diberi opsi untuk menautkan dengan email yang berbeda.
      2. TIDAK : Alur OAuth Web dipicu, pengguna diarahkan ke browsernya, dan pengguna diberi opsi untuk menautkan dengan email yang berbeda.
   2. TIDAK : Apakah pengguna memiliki akun yang cocok di sistem autentikasi Anda? (check intent dipanggil untuk mengonfirmasi)
      1. YA : get intent dipanggil dan akun ditautkan jika intent get berhasil ditampilkan.
      2. TIDAK : create intent dipanggil dan akun ditautkan jika intent create berhasil ditampilkan.

Memeriksa akun pengguna yang ada (periksa intent)

Setelah pengguna memberikan izin untuk mengakses profil Google miliknya, Google akan mengirimkan yang berisi pernyataan bertanda tangan tentang identitas pengguna Google. Tujuan berisi informasi yang menyertakan ID Akun Google pengguna, nama, dan alamat email. Endpoint pertukaran token yang dikonfigurasi untuk project menangani permintaan tersebut.

Jika Akun Google yang sesuai sudah ada dalam autentikasi Anda endpoint, endpoint pertukaran token akan merespons dengan account_found=true. Jika Akun Google tidak cocok dengan pengguna yang ada, endpoint pertukaran token Anda menampilkan error HTTP 404 Not Found dengan account_found=false.

Permintaan tersebut memiliki bentuk berikut:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&intent=check&assertion=JWT&scope=SCOPES&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

Endpoint pertukaran token Anda harus dapat menangani parameter berikut:

Untuk merespons permintaan intent check, endpoint pertukaran token Anda harus melakukan langkah-langkah berikut:

• Validasi dan dekode pernyataan JWT.
• Periksa apakah Akun Google sudah ada dalam sistem autentikasi Anda.

Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example:

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

• email has a @gmail.com suffix, this is a Gmail account.
• email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

Periksa apakah Akun Google sudah ada dalam sistem autentikasi Anda

Periksa apakah salah satu kondisi berikut terpenuhi:

• ID Akun Google, yang ada di kolom sub pernyataan, berada di pengguna Anda di skrip untuk menyiapkan database.
• Alamat email dalam pernyataan cocok dengan pengguna di database pengguna Anda.

Jika salah satu kondisinya benar, pengguna sudah mendaftar. Dalam kasus tersebut, tampilkan respons seperti berikut:

HTTP/1.1 200 Success
Content-Type: application/json;charset=UTF-8

{
  "account_found":"true",
}

Jika ID Akun Google atau alamat email tidak disebutkan dalam cocok dengan pengguna di database Anda, pengguna tersebut belum mendaftar. Di beberapa dalam kasus ini, endpoint pertukaran token Anda harus membalas dengan error HTTP 404 yang menentukan "account_found": "false", seperti dalam contoh berikut:

HTTP/1.1 404 Not found
Content-Type: application/json;charset=UTF-8

{
  "account_found":"false",
}

Handle automatic linking (get intent)

After the user gives consent to access their Google profile, Google sends a request that contains a signed assertion of the Google user's identity. The assertion contains information that includes the user's Google Account ID, name, and email address. The token exchange endpoint configured for your project handles that request.

If the corresponding Google Account is already present in your authentication system, your token exchange endpoint returns a token for the user. If the Google Account doesn't match an existing user, your token exchange endpoint returns a linking_error error and optional login_hint.

The request has the following form:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&intent=get&assertion=JWT&scope=SCOPES&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

Your token exchange endpoint must be able to handle the following parameters:

To respond to the get intent requests, your token exchange endpoint must perform the following steps:

• Validate and decode the JWT assertion.
• Check if the Google account is already present in your authentication system.

Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example:

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

• email has a @gmail.com suffix, this is a Gmail account.
• email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

Check if the Google account is already present in your authentication system

Check whether either of the following conditions are true:

• The Google Account ID, found in the assertion's sub field, is in your user database.
• The email address in the assertion matches a user in your user database.

If an account is found for the user, issue an access token and return the values in a JSON object in the body of your HTTPS response, like in the following example:

{
  "token_type": "Bearer",
  "access_token": "ACCESS_TOKEN",
  "refresh_token": "REFRESH_TOKEN",
  "expires_in": SECONDS_TO_EXPIRATION
}

In some cases, account linking based on ID token might fail for the user. If it does so for any reason, your token exchange endpoint needs to reply with a HTTP 401 error that specifies error=linking_error, as the following example shows:

HTTP/1.1 401 Unauthorized
Content-Type: application/json;charset=UTF-8

{
  "error":"linking_error",
  "login_hint":"foo@bar.com"
}

When Google receives a 401 error response with linking_error, Google sends the user to your authorization endpoint with login_hint as a parameter. The user completes account linking using the OAuth linking flow in their browser.

Handle account creation via Google Sign-In (create intent)

When a user needs to create an account on your service, Google makes a request to your token exchange endpoint that specifies intent=create.

The request has the following form:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

response_type=token&grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&scope=SCOPES&intent=create&assertion=JWT&client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET

Your token exchange endpoint must able to handle the following parameters:

The JWT within the assertion parameter contains the user's Google Account ID, name, and email address, which you can use to create a new account on your service.

To respond to the create intent requests, your token exchange endpoint must perform the following steps:

• Validate and decode the JWT assertion.
• Validate user information and create new account.

Validate and decode the JWT assertion

You can validate and decode the JWT assertion by using a JWT-decoding library for your language. Use Google's public keys, available in JWK or PEM formats, to verify the token's signature.

When decoded, the JWT assertion looks like the following example:

{
  "sub": "1234567890",      // The unique ID of the user's Google Account
  "iss": "https://accounts.google.com",        // The assertion's issuer
  "aud": "123-abc.apps.googleusercontent.com", // Your server's client ID
  "iat": 233366400,         // Unix timestamp of the assertion's creation time
  "exp": 233370000,         // Unix timestamp of the assertion's expiration time
  "name": "Jan Jansen",
  "given_name": "Jan",
  "family_name": "Jansen",
  "email": "jan@gmail.com", // If present, the user's email address
  "email_verified": true,   // true, if Google has verified the email address
  "hd": "example.com",      // If present, the host domain of the user's GSuite email address
                            // If present, a URL to user's profile picture
  "picture": "https://lh3.googleusercontent.com/a-/AOh14GjlTnZKHAeb94A-FmEbwZv7uJD986VOF1mJGb2YYQ",
  "locale": "en_US"         // User's locale, from browser or phone settings
}

In addition to verifying the token's signature, verify that the assertion's issuer (iss field) is https://accounts.google.com, that the audience (aud field) is your assigned client ID, and that the token has not expired (exp field).

Using the email, email_verified and hd fields you can determine if Google hosts and is authoritative for an email address. In cases where Google is authoritative the user is currently known to be the legitimate account owner and you may skip password or other challenges methods. Otherwise, these methods can be used to verify the account prior to linking.

Cases where Google is authoritative:

• email has a @gmail.com suffix, this is a Gmail account.
• email_verified is true and hd is set, this is a G Suite account.

Users may register for Google Accounts without using Gmail or G Suite. When email does not contain a @gmail.com suffix and hd is absent Google is not authoritative and password or other challenge methods are recommended to verify the user. email_verified can also be true as Google initially verified the user when the Google account was created, however ownership of the third party email account may have since changed.

Validate user information and create new account

Check whether either of the following conditions are true:

• The Google Account ID, found in the assertion's sub field, is in your user database.
• The email address in the assertion matches a user in your user database.

If either condition is true, prompt the user to link their existing account with their Google Account. To do so, respond to the request with an HTTP 401 error that specifies error=linking_error and gives the user's email address as the login_hint. The following is a sample response:

HTTP/1.1 401 Unauthorized
Content-Type: application/json;charset=UTF-8

{
  "error":"linking_error",
  "login_hint":"foo@bar.com"
}

When Google receives a 401 error response with linking_error, Google sends the user to your authorization endpoint with login_hint as a parameter. The user completes account linking using the OAuth linking flow in their browser.

If neither condition is true, create a new user account with the information provided in the JWT. New accounts don't typically have a password set. It's recommended that you add Google Sign-In to other platforms to enable users to log in with Google across the surfaces of your application. Alternatively, you can email the user a link that starts your password recovery flow to allow the user to set a password to sign in on other platforms.

When the creation is completed, issue an access token and return the values in a JSON object in the body of your HTTPS response, like in the following example:

{
  "token_type": "Bearer",
  "access_token": "ACCESS_TOKEN",
  "refresh_token": "REFRESH_TOKEN",
  "expires_in": SECONDS_TO_EXPIRATION
}

Mendapatkan Client ID Google API

Anda akan diminta untuk memberikan Client ID Google API selama proses pendaftaran Penautan Akun.

Untuk mendapatkan Client ID API menggunakan project yang Anda buat saat menyelesaikan langkah-langkah Penautan OAuth. Caranya, selesaikan langkah-langkah berikut:

2. Buat atau pilih project Google API.

   Jika project Anda tidak memiliki Client ID untuk Jenis aplikasi web, klik Buat Klien untuk membuatnya. Pastikan untuk menyertakan domain situs Anda di kotak Asal JavaScript yang sah. Saat melakukan pengujian atau pengembangan lokal, Anda harus menambahkan http://localhost dan http://localhost:<port_number> ke kolom Asal JavaScript yang diotorisasi.

Memvalidasi implementasi

您可以使用 OAuth 2.0 Playground 工具验证您的实现。

在该工具中，执行以下步骤：

1. 点击配置 settings 以打开 OAuth 2.0 配置窗口。
2. 在 OAuth flow 字段中，选择 Client-side（客户端）。
3. 在 OAuth 端点字段中，选择自定义。
4. 在相应字段中指定您的 OAuth 2.0 端点和您分配给 Google 的客户端 ID。
5. 在第 1 步部分，不要选择任何 Google 范围。请将此字段留空或输入对服务器有效的范围（如果您不使用 OAuth 范围，则可以输入任意字符串）。完成后，点击授权 API。
6. 在 Step 2 和 Step 3 部分中，完成 OAuth 2.0 流程，并验证每个步骤是否按预期运行。

您可以使用 Google 账号关联演示版工具验证您的实现。

在该工具中，执行以下步骤：

1. 点击使用 Google 账号登录按钮。
2. 选择您要关联的账号。
3. 输入服务 ID。
4. （可选）输入您要请求访问权限的一个或多个范围。
5. 点击开始演示。
6. 当系统提示时，请确认您同意或拒绝关联请求。
7. 确认您已被重定向到您的平台。