OAuth로 Google 계정 연결

계정은 업계 표준 OAuth 2.0 암시적 흐름 및 승인 코드 흐름을 사용하여 연결됩니다. 서비스가 OAuth 2.0을 준수하는 승인 및 토큰 교환 엔드포인트를 지원해야 합니다.

In the implicit flow, Google opens your authorization endpoint in the user's browser. After successful sign in, you return a long-lived access token to Google. This access token is now included in every request sent from Google.

In the authorization code flow, you need two endpoints:

• The authorization endpoint, which presents the sign-in UI to your users that aren't already signed in. The authorization endpoint also creates a short-lived authorization code to record users' consent to the requested access.

• The token exchange endpoint, which is responsible for two types of exchanges:

  1. Exchanges an authorization code for a long-lived refresh token and a short-lived access token. This exchange happens when the user goes through the account linking flow.
  2. Exchanges a long-lived refresh token for a short-lived access token. This exchange happens when Google needs a new access token because the one it had expired.

Choose an OAuth 2.0 flow

Although the implicit flow is simpler to implement, Google recommends that access tokens issued by the implicit flow never expire. This is because the user is forced to link their account again after a token expires with the implicit flow. If you need token expiration for security reasons, we strongly recommend that you use the authorization code flow instead.

Design guidelines

This section describes the design requirements and recommendations for the user screen that you host for OAuth linking flows. After it's called by Google's app, your platform displays a sign in to Google page and account linking consent screen to the user. The user is directed back to Google's app after giving their consent to link accounts.

Requirements

1. You must communicate that the user’s account will be linked to Google, not a specific Google product like Google Home or Google Assistant.

Recommendations

We recommend that you do the following:

1. Display Google's Privacy Policy. Include a link to Google’s Privacy Policy on the consent screen.

2. Data to be shared. Use clear and concise language to tell the user what data of theirs Google requires and why.

3. Clear call-to-action. State a clear call-to-action on your consent screen, such as “Agree and link.” This is because users need to understand what data they're required to share with Google to link their accounts.

4. Ability to cancel. Provide a way for users to go back or cancel, if they choose not to link.

5. Clear sign-in process. Ensure that users have clear method for signing in to their Google account, such as fields for their username and password or Sign in with Google.

6. Ability to unlink. Offer a mechanism for users to unlink, such as a URL to their account settings on your platform. Alternatively, you can include a link to Google Account where users can manage their linked account.

7. Ability to change user account. Suggest a method for users to switch their account(s). This is especially beneficial if users tend to have multiple accounts.

   • If a user must close the consent screen to switch accounts, send a recoverable error to Google so the user can sign in to the desired account with OAuth linking and the implicit flow.

8. Include your logo. Display your company logo on the consent screen. Use your style guidelines to place your logo. If you wish to also display Google's logo, see Logos and trademarks.

프로젝트 만들기

계정 연결을 사용할 프로젝트를 만들려면 다음 단계를 따르세요.

2. 프로젝트 만들기를 클릭합니다.
3. 이름을 입력하거나 생성된 추천을 수락합니다.
4. 나머지 필드를 확인하거나 수정합니다.
5. 만들기를 클릭합니다.

프로젝트 ID를 확인하려면 다음 단계를 따르세요.

2. 방문 페이지의 표에서 프로젝트를 찾습니다. 프로젝트 ID는 ID 열에 표시됩니다.

OAuth 동의 화면 구성

Google 계정 연결 프로세스에는 사용자에게 데이터 액세스를 요청하는 애플리케이션, 요청하는 데이터의 종류, 적용되는 약관을 알려주는 동의 화면이 포함됩니다. Google API 클라이언트 ID를 생성하기 전에 OAuth 동의 화면을 구성해야 합니다.

1. Google API 콘솔의 OAuth 동의 화면 페이지를 엽니다.
2. 메시지가 표시되면 방금 만든 프로젝트를 선택합니다.

3. 'OAuth 동의 화면' 페이지에서 양식을 작성하고 '저장' 버튼을 클릭합니다.

   애플리케이션 이름: 동의를 요청하는 애플리케이션의 이름입니다. 이름은 애플리케이션을 정확하게 반영해야 하며 사용자가 다른 곳에서 보는 애플리케이션 이름과 일치해야 합니다. 애플리케이션 이름은 계정 연결 동의 화면에 표시됩니다.

   애플리케이션 로고: 사용자가 앱을 인식하는 데 도움이 되는 동의 화면의 이미지입니다. 로고는 계정 연결 동의 화면과 계정 설정에 표시됩니다.

   지원 이메일: 사용자가 동의에 대해 문의할 수 있습니다.

   Google API 범위: 범위를 사용하면 애플리케이션이 사용자의 비공개 Google 데이터에 액세스할 수 있습니다. Google 계정 연결 사용 사례의 경우 기본 범위 (이메일, 프로필, openid)로 충분하며 민감한 범위를 추가할 필요가 없습니다. 일반적으로 액세스가 필요한 시점에 미리 요청하는 대신 점진적으로 범위를 요청하는 것이 좋습니다. 자세히 알아보기

   승인된 도메인: 나와 내 사용자를 보호하기 위해 Google에서는 OAuth를 사용하여 인증하는 애플리케이션만 승인된 도메인을 사용할 수 있도록 허용합니다. 애플리케이션의 링크는 승인된 도메인에서 호스팅되어야 합니다. 자세히 알아보기

   애플리케이션 홈페이지 링크: 애플리케이션의 홈페이지입니다. 승인된 도메인에서 호스팅해야 합니다.

   애플리케이션 개인정보처리방침 링크: Google 계정 연결 동의 화면에 표시됩니다. 승인된 도메인에서 호스팅해야 합니다.

   애플리케이션 서비스 약관 링크 (선택사항): 승인된 도메인에서 호스팅되어야 합니다.

   

   그림 1. 가상 애플리케이션 Tunery의 Google 계정 연결 동의 화면

4. '인증 상태'를 확인합니다. 애플리케이션에 인증이 필요한 경우 '인증을 위해 제출' 버튼을 클릭하여 인증을 위해 애플리케이션을 제출합니다. 자세한 내용은 OAuth 인증 요구사항을 참고하세요.

OAuth 서버 구현

An OAuth 2.0 server implementation of the authorization code flow consists of two endpoints, which your service makes available by HTTPS. The first endpoint is the authorization endpoint, which is responsible for finding or 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. The second endpoint is the token exchange endpoint, which is used to obtain encrypted strings, called tokens, that authorize a user to access your service.

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

An OAuth 2.0 authorization code flow session initiated by Google has the following flow:

1. Google opens your authorization endpoint in the user's browser. If the flow started on a voice-only device for an Action, Google transfers the execution to a phone.
2. 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.
3. Your service creates an authorization code and returns it to Google. To do so, redirect the user's browser back to Google with the authorization code attached to the request.
4. Google sends the authorization code to your token exchange endpoint, which verifies the authenticity of the code and returns an access token and a refresh token. The access token is a short-lived token that your service accepts as credentials to access APIs. The refresh token is a long-lived token that Google can store and use to acquire new access tokens when they expire.
5. After the user has completed the account linking flow, every subsequent request sent from Google contains an access token.

Handle authorization requests

When you need to perform account linking using the OAuth 2.0 authorization code flow, Google sends the user to your authorization endpoint with a request that includes the following parameters:

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&scope=REQUESTED_SCOPES&response_type=code&user_locale=LOCALE

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

1. Verify that the client_id matches the Client ID you assigned to Google, and that the redirect_uri matches the redirect URL provided by Google for your service. These checks are important to prevent granting access to unintended or misconfigured client apps. If you support multiple OAuth 2.0 flows, also confirm that the response_type is code.
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 authorization code for Google to use to access your API. The authorization code can be any string value, but it must uniquely represent the user, the client the token is for, and the code's expiration time, and it must not be guessable. You typically issue authorization codes that expire after approximately 10 minutes.
4. 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
     

5. Redirect the user's browser to the URL specified by the redirect_uri parameter. Include the authorization code you just generated and the original, unmodified state value when you redirect by appending the code and state parameters. The following is an example of the resulting URL:

   https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID?code=AUTHORIZATION_CODE&state=STATE_STRING

Handle token exchange requests

Your service's token exchange endpoint is responsible for two kinds of token exchanges:

• Exchange authorization codes for access tokens and refresh tokens
• Exchange refresh tokens for access tokens

Token exchange requests include the following parameters:

Exchange authorization codes for access tokens and refresh tokens

After the user signs in and your authorization endpoint returns a short-lived authorization code to Google, Google sends a request to your token exchange endpoint to exchange the authorization code for an access token and a refresh token.

For these requests, the value of grant_type is authorization_code, and the value of code is the value of the authorization code you previously granted to Google. The following is an example of a request to exchange an authorization code for an access token and a refresh token:

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

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=authorization_code&code=AUTHORIZATION_CODE&redirect_uri=REDIRECT_URI

To exchange authorization codes for an access token and a refresh token, your token exchange endpoint responds to POST requests by executing the following steps:

1. Verify that the client_id identifies the request origin as an authorized origin, and that the client_secret matches the expected value.
2. Verify that the authorization code is valid and not expired, and that the client ID specified in the request matches the client ID associated with the authorization code.
3. Confirm that the URL specified by the redirect_uri parameter is identical to the value used in the initial authorization request.
4. If you can't verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
5. Otherwise, use the user ID from the authorization code to generate a refresh token and an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token, which is typically an hour after you issue the token. Refresh tokens don't expire.
6. Return the following JSON object in the body of the HTTPS response:

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

Google stores the access token and the refresh token for the user and records the expiration of the access token. When the access token expires, Google uses the refresh token to get a new access token from your token exchange endpoint.

Exchange refresh tokens for access tokens

When an access token expires, Google sends a request to your token exchange endpoint to exchange a refresh token for a new access token.

For these requests, the value of grant_type is refresh_token, and the value of refresh_token is the value of the refresh token you previously granted to Google. The following is an example of a request to exchange a refresh token for an access token:

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

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=refresh_token&refresh_token=REFRESH_TOKEN

To exchange a refresh token for an access token, your token exchange endpoint responds to POST requests by executing the following steps:

1. Verify that the client_id identifies the request origin as Google, and that the client_secret matches the expected value.
2. Verify that the refresh token is valid, and that the client ID specified in the request matches the client ID associated with the refresh token.
3. If you can't verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
4. Otherwise, use the user ID from the refresh token to generate an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token, typically an hour after you issue the token.
5. Return the following JSON object in the body of the HTTPS response:

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

사용자 정보 요청 처리

userinfo 엔드포인트는 연결된 사용자에 대한 클레임을 반환하는 OAuth 2.0 보호 리소스입니다. 다음 사용 사례를 제외하고 userinfo 엔드포인트를 구현하고 호스팅하는 것은 선택사항입니다.

• Google 원탭을 사용한 연결된 계정 로그인
• AndroidTV의 원활한 구독

토큰 엔드포인트에서 액세스 토큰을 성공적으로 가져오면 Google은 사용자 정보 엔드포인트에 요청을 보내 연결된 사용자에 대한 기본 프로필 정보를 가져옵니다.

예를 들어 https://myservice.example.com/userinfo인 경우 요청은 다음과 같을 수 있습니다.

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

userinfo 엔드포인트에서 요청을 처리하려면 다음 단계를 수행합니다.

1. 승인 헤더에서 액세스 토큰을 추출하고 액세스 토큰과 연결된 사용자의 정보를 반환합니다.
2. 액세스 토큰이 유효하지 않은 경우 WWW-Authenticate 응답 헤더를 사용하여 HTTP 401 승인되지 않은 오류를 반환합니다. 다음은 userinfo 오류 응답의 예입니다.

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

   드림 연결 과정 중에 401 승인되지 않음 또는 기타 실패한 오류 응답이 반환되면 오류는 복구할 수 없으며 검색된 토큰은 삭제되며 사용자는 연결 프로세스를 다시 시작해야 합니다.

3. 액세스 토큰이 유효하면 HTTPS 본문에 다음 JSON 객체가 포함된 HTTP 200 응답을 반환합니다. 응답:

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

   드림 userinfo 엔드포인트가 HTTP 200 성공 응답을 반환하는 경우 가져온 토큰과 클레임은 사용자의 Google 계정에 등록됩니다.

   사용자 정보 엔드포인트 응답
   sub	시스템에서 사용자를 식별하는 고유 ID
   email	사용자의 이메일 주소입니다.
   given_name	선택사항: 사용자의 이름입니다.
   family_name	선택사항: 사용자의 성.
   name	선택사항: 사용자의 전체 이름입니다.
   picture	선택사항: 사용자의 프로필 사진입니다.

구현 확인

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

In the tool, do the following steps:

1. Click Configuration settings 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.