Übersicht
Optimierte Verknüpfung mit OAuth-basiertem Google Log-in: Google Log-in ergänzt OAuth-Verknüpfung. Dies ermöglicht eine nahtlose Verknüpfung von .
Um Kontoverknüpfungen mit OAuth und Google Log-in durchzuführen, folge diesen allgemeinen Schritte:
- Bitten Sie den Nutzer zuerst, seine Einwilligung für den Zugriff auf sein Google-Profil zu geben.
- Anhand der Informationen in ihrem Profil können Sie prüfen, ob das Nutzerkonto vorhanden ist.
- Verknüpfen Sie die Konten für bestehende Nutzer.
- Wenn Sie in Ihrem Authentifizierungssystem keine Übereinstimmung für den Google-Nutzer finden können, Validieren Sie das von Google erhaltene ID-Token. Sie können dann ein nutzerbasiertes zu den Profilinformationen im ID-Token.
Abbildung 1. Kontoverknüpfung auf dem Smartphone eines Nutzers mit der optimierten Verknüpfung
Anforderungen für optimierte Verknüpfungen
- Implementiere den einfachen OAuth-Verknüpfungsvorgang für das Web. Ihr Dienst muss OAuth 2.0-konform unterstützen Endpunkte Autorisierung und Tokenaustausch.
- Ihr Endpunkt für den Tokenaustausch muss JSON Web Token (JWT)-Assertions unterstützen und die Intents
check
,create
undget
implementieren.
OAuth-Server implementieren
Der Endpunkt des Tokenaustauschs muss die Intents check
, create
und get
unterstützen. Unten sehen Sie die Schritte, die während der Kontoverknüpfung ausgeführt werden, und es wird angegeben, wann die verschiedenen Intents aufgerufen werden:
- Hat der Nutzer ein Konto in Ihrem Authentifizierungssystem? (Der Nutzer entscheidet sich mit Ja oder NEIN.)
<ph type="x-smartling-placeholder">
- </ph>
- JA : Nutzt der Nutzer die E-Mail-Adresse, die mit seinem Google-Konto verknüpft ist, um sich auf Ihrer Plattform anzumelden? (Der Nutzer entscheidet sich mit Ja oder NEIN.)
<ph type="x-smartling-placeholder">
- </ph>
- JA : Verfügt der Nutzer über ein übereinstimmendes Konto in Ihrem Authentifizierungssystem? (
check intent
wird zur Bestätigung aufgerufen) <ph type="x-smartling-placeholder">- </ph>
- JA :
get intent
wird aufgerufen und das Konto wird verknüpft, wenn der get-Intent erfolgreich zurückgegeben wird. - NEIN : Neues Konto erstellen? (Der Nutzer entscheidet sich mit Ja oder NEIN.)
<ph type="x-smartling-placeholder">
- </ph>
- JA :
create intent
wird aufgerufen und das Konto verknüpft, wenn der Erstellungs-Intent erfolgreich zurückgegeben wird. - NEIN : Der Web-OAuth-Ablauf wird ausgelöst, der Nutzer wird zu seinem Browser weitergeleitet und erhält die Möglichkeit, eine Verknüpfung mit einer anderen E-Mail-Adresse herzustellen.
- JA :
- JA :
- NEIN : Der Web-OAuth-Vorgang wird ausgelöst, der Nutzer wird zu seinem Browser weitergeleitet und hat die Möglichkeit, eine Verknüpfung mit einer anderen E-Mail-Adresse herzustellen.
- JA : Verfügt der Nutzer über ein übereinstimmendes Konto in Ihrem Authentifizierungssystem? (
- NEIN : Verfügt der Nutzer über ein übereinstimmendes Konto in Ihrem Authentifizierungssystem? (
check intent
wird zur Bestätigung aufgerufen) <ph type="x-smartling-placeholder">- </ph>
- JA :
get intent
wird aufgerufen und das Konto wird verknüpft, wenn der get-Intent erfolgreich zurückgegeben wird. - NEIN :
create intent
wird aufgerufen und das Konto verknüpft, wenn die Rückgabe des Intents zum Erstellen erfolgreich ist.
- JA :
- JA : Nutzt der Nutzer die E-Mail-Adresse, die mit seinem Google-Konto verknüpft ist, um sich auf Ihrer Plattform anzumelden? (Der Nutzer entscheidet sich mit Ja oder NEIN.)
<ph type="x-smartling-placeholder">
Check for an existing user account (check 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 responds with account_found=true
. If the
Google account doesn't match an existing user, your token exchange endpoint
returns an HTTP 404 Not Found error with account_found=false
.
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=check&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:
Token endpoint parameters | |
---|---|
intent |
For these requests, the value of this parameter is
check . |
grant_type |
The type of token being exchanged. For these requests, this
parameter has the value urn:ietf:params:oauth:grant-type:jwt-bearer . |
assertion |
A JSON Web Token (JWT) that provides a signed assertion of the Google user's identity. The JWT contains information that includes the user's Google Account ID, name, and email address. |
client_id |
The client ID you assigned to Google. |
client_secret |
The client secret you assigned to Google. |
To respond to the check
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 andhd
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 either condition is true, the user has already signed up. In that case, return a response like the following:
HTTP/1.1 200 Success Content-Type: application/json;charset=UTF-8 { "account_found":"true", }
If neither the Google Account ID nor the email address specified in the
assertion matches a user in your database, the user hasn't signed up yet. In
this case, your token exchange endpoint needs to reply with a HTTP 404 error
that specifies "account_found": "false"
, as in the following example:
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:
Token endpoint parameters | |
---|---|
intent |
For these requests, the value of this parameter is get . |
grant_type |
The type of token being exchanged. For these requests, this
parameter has the value urn:ietf:params:oauth:grant-type:jwt-bearer . |
assertion |
A JSON Web Token (JWT) that provides a signed assertion of the Google user's identity. The JWT contains information that includes the user's Google Account ID, name, and email address. |
scope |
Optional: Any scopes that you've configured Google to request from users. |
client_id |
The client ID you assigned to Google. |
client_secret |
The client secret you assigned to Google. |
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 andhd
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:
Token endpoint parameters | |
---|---|
intent |
For these requests, the value of this parameter is create . |
grant_type |
The type of token being exchanged. For these requests, this
parameter has the value urn:ietf:params:oauth:grant-type:jwt-bearer . |
assertion |
A JSON Web Token (JWT) that provides a signed assertion of the Google user's identity. The JWT contains information that includes the user's Google Account ID, name, and email address. |
client_id |
The client ID you assigned to Google. |
client_secret |
The client secret you assigned to Google. |
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 andhd
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 refresh 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 }
Google API-Client-ID abrufen
Sie müssen Ihre Google API-Client-ID bei der Registrierung der Kontoverknüpfung angeben.
API-Client-ID über das Projekt abrufen, das Sie bei der OAuth-Verknüpfung erstellt haben Führen Sie dazu folgende Schritte aus:
- Öffnen Sie die Seite Anmeldedaten des Google API Console:
Erstellen Sie ein Google APIs-Projekt oder wählen Sie eines aus.
Wenn Ihr Projekt keine Client-ID für den Webanwendungstyp hat, klicken Sie auf Anmeldedaten erstellen > OAuth-Client-ID, um eine zu erstellen. Achten Sie darauf, Ihre Websitedomain im Feld Autorisierte JavaScript-Quellen ein. Wenn Sie lokale Tests oder die Entwicklung vor Ort verwenden, müssen Sie sowohl
http://localhost
als auchhttp://localhost:<port_number>
in das Feld Autorisierte JavaScript-Quellen ein.
Implementierung validieren
Sie können Ihre Implementierung mit dem Tool OAuth 2.0 Playground validieren.
Führen Sie im Tool die folgenden Schritte aus:
- Klicken Sie auf Konfiguration , um das Fenster für die OAuth 2.0-Konfiguration zu öffnen.
- Wählen Sie im Feld OAuth-Ablauf die Option Clientseitig aus.
- Wählen Sie im Feld OAuth-Endpunkte die Option Benutzerdefiniert aus.
- Geben Sie in den entsprechenden Feldern Ihren OAuth 2.0-Endpunkt und die Client-ID an, die Sie Google zugewiesen haben.
- Wählen Sie im Abschnitt Schritt 1 keine Google-Bereiche aus. Lassen Sie dieses Feld stattdessen leer oder geben Sie einen für Ihren Server gültigen Bereich ein (oder einen beliebigen String, wenn Sie keine OAuth-Bereiche verwenden). Wenn Sie fertig sind, klicken Sie auf APIs autorisieren.
- Führen Sie in den Abschnitten Schritt 2 und Schritt 3 den OAuth 2.0-Ablauf durch und prüfen Sie, ob jeder Schritt wie vorgesehen funktioniert.
Sie können Ihre Implementierung mit der Demo zur Google-Kontoverknüpfung prüfen.
Führen Sie im Tool die folgenden Schritte aus:
- Klicken Sie auf die Schaltfläche Über Google anmelden.
- Wählen Sie das Konto aus, das Sie verknüpfen möchten.
- Geben Sie die Service-ID ein.
- Optional können Sie einen oder mehrere Bereiche angeben, für die Sie Zugriff anfordern möchten.
- Klicken Sie auf Demo starten.
- Bestätigen Sie bei Aufforderung, dass Sie der Verknüpfungsanfrage zustimmen oder sie ablehnen können.
- Prüfen Sie, ob Sie zu Ihrer Plattform weitergeleitet werden.