Migrating from OpenID 2.0 to OpenID Connect

This document provides details about migrating your code from OpenID 2.0 to OpenID Connect. We recommend you use Google Sign-in, which is our client library that provides OpenID Connect sign-in for Google Accounts. You can also use our OpenID Connect endpoints directly. This document provides information about both migration strategies.

Migrating to Google Sign-In

If you provide a "sign-in with Google" feature, we recommend using Google Sign-In. Google Sign-In provides OAuth 2.0 (OpenID Connect) authentication with access to additional Google desktop and mobile features. Google Sign-In supports transparent migration and offers widgets and client libraries that make it easy to implement. It supports all users who have a Google account, whether or not they've upgraded to Google+.

If you currently have OpenID 2.0–based software in production, or if you have users who are known only by an OpenID 2.0 identifier, you can switch to Google Sign-In without losing track of your existing users by linking the OpenID 2.0 account identifiers to new Google Sign-In identifiers, then using the new identifiers going forward. For details, see the step-by-step instructions for switching from OpenID 2.0 to Google Sign-In.

If you switch to Google Sign-In, here are some tips:

  • If users have provided email addresses to your app via OpenID 2.0 and you do not want these users to be asked to re-consent when you switch to Google Sign-In, use only the email scope.
  • To configure Google Sign-In to return profile information in OpenID Connect format, use the openid scope and get the user profile by calling the people.getOpenIdConnect endpoint.

If your OpenID 2.0–based app is on a platform not supported by Google Sign-In, or if you want to work directly with the OAuth 2.0 REST APIs, then we recommend migrating to Google's OpenID Connect solution, as described below.

Migrating to OpenID Connect

The basic techniques for logging in with OpenID Connect are described in Using OAuth 2.0 for Login (OpenID Connect). You can introduce OpenID Connect–based authentication into your OpenID 2.0 authentication process without losing track of existing users' accounts by following these steps:

  • Step 1: Adjust the authentication request URI that you send to Google by adding openid.realm and other parameters.
  • Step 2: Update your sign-in code to use an OpenID Connect authentication process.
  • Step 3: Map existing OpenID 2.0 identifiers to new OpenID Connect identifiers and add the new identifiers to your user database.

Step 1: Adjust the authentication request URI that you send to Google

When you construct an authentication request to send to Google, it is in the form of a URI that begins with Google's OAuth 2.0 endpoint, https://accounts.google.com/o/oauth2/auth. You construct the rest of the URI by adding parameters as needed. For applications that use OpenID 2.0, the authentication request URI may include an openid.realm parameter, and can also include the login_hint and other parameters.

If you are migrating your code from OpenID 2.0, set up your OpenID Connect authentication requests as follows:

  1. If you have not yet done so, obtain OAuth 2.0 credentials for your project from the Google Developers Console.
  2. In the Developers Console, find your application's redirect_uri and change it (if necessary) so that it matches your OpenID 2.0 openid.realm value, according to the matching rules in section 9.2 of the OpenID 2.0 spec.

    To find the redirect URIs for your OAuth 2.0 credentials, do the following:

    1. Open the Credentials page.
    2. If you haven't done so already, create your OAuth 2.0 credentials by clicking Add credentials > OAuth 2.0 client ID.
    3. After you create your credentials, view or edit the redirect URLs by clicking the client ID in the OAuth 2.0 client IDs section.

  3. When you construct your OpenID Connect authentication URI, include an extra argument, the openid.realm parameter. Use the same value that you used for the openid.realm parameter in your OpenID 2.0 requests.

  4. You must also include a scope parameter that requests access to the user ID. We recommend using the email scope, which allows your app to get basic profile information from users who have upgraded to Google+. In some situations when you use the email scope, users are not required to re-consent. The user is not presented with a consent screen if all the following are true:

    • The user has provided an email address to your application via OpenID 2.0, and
    • You request only the email scope, and
    • The access type for your request is online, which is the default. (Note that when OpenID access is granted, it is always for online access, so a refresh token cannot be returned from these requests. For more about access_type, see Authentication URI parameters.)

    If these three conditions are met, the user's account information is migrated to the email scope.

    Instead of the email scope, you can specify profile or plus.login. The profile scope allows your app to get some profile information for users who have not yet upgraded to Google+, but because it expands your app's access to user data, this scope will require users to re-consent. The plus.login scope gives you access to write to the user's history and see the people in their circles.

  5. If you know the user's email address, include it in the authentication URI as the value of the login_hint parameter. If you do not include a login_hint and the user is signed into Google with multiple accounts, they will see an "account chooser" asking them to select one account. This might be surprising to them, and they might select an account other than the one your application is trying to authorize, which could increase the complexity of your task.

Step 2: Update your sign-in code

Update your sign-in code so that it launches an OpenID Connect authentication process instead of an OpenID 2.0 authentication process:

  • Use the people.getOpenIdConnect endpoint, either by using the following HTTP request path, or by using the corresponding client library call:
    • https://www.googleapis.com/plus/v1/people/me/openIdConnect

  • No change is needed to the OpenID Connect scopes openid, profile, and email.

The response includes basic user data in the OpenID Connect format.

Step 3: Map OpenID 2.0 identifiers to OpenID Connect identifiers

When you send an OpenID Connect authentication request URI to Google as described in Step 1, you include an openid.realm parameter. The response that is sent to your redirect_uri includes an authorization code that your application can use to retrieve an access token and an ID token. (You can also retrieve an ID token directly from the OpenID Connect authentication request by adding id_token to the response_type parameter, potentially saving a back-end call to the token endpoint.)

The response from that token request includes the usual fields (access_token, etc.), plus an openid_id field and the standard OpenID Connect sub field. The fields you need in this context are openid_id and sub:

  • The openid_id field holds the OpenID 2.0 identifier. OpenID 2.0 identifiers are strings that begin with https://www.google.com/accounts/o8/id?id=.
  • The sub field holds the OpenID Connect identifier (which corresponds to the id field of the Google+ people.get response). OpenID Connect identifiers are long numeric strings such as 1016730112881507946.

To migrate your sign-in infrastructure from OpenID 2.0 to OpenID Connect, add code to your application that does the following for each response that you receive from a token request:

  1. Extract the sub field from the token-request response. This is the OpenID Connect identifier.
  2. In your user database, link the openid_id to the new sub ID.
  3. Use the new IDs going forward.

Migrating a hybrid login solution

If your app uses a hybrid OpenID 2.0 / OAuth 1.0 login solution, you must migrate your app by the deadlines given in the migration timetable. We recommend that you switch to Google Sign-In. For step-by-step instructions, see Migrate from OpenID 2.0 or OpenID+OAuth hybrid to Google Sign-In.

If for some reason you need to work directly with the OpenID Connect OAuth 2.0 protocols, it is possible to migrate the two components of your app separately:

The general information in Implementing OAuth with federated login (hybrid protocol) still applies.

Migrating how your app gets email addresses

If you use the deprecated userinfo endpoint to get user email addresses, you must migrate how your app gets email addresses.