Authentication and authorization are mechanisms used to verify identity and access to resources, respectively. This document outlines how authentication and authorization work for Chat apps and Chat API requests.
Process overview
The following diagram shows the high-level steps of authentication and authorization for Google Chat:
Configure a Google Cloud project, enable Chat API, and configure your Chat app: During development, you create a Google Cloud project. In the Google Cloud project, you enable Chat API, configure your Chat app, and set up authentication. For more information, see Develop on Google Workspace and Build a Chat app.
Call Chat API: When your app calls the Chat API, it sends authentication credentials to the Chat API. If your app authenticates with a service account, the credentials are sent as part of your app's code. If your app requires calling Chat API using a user's authentication that hasn't yet been granted, it prompts the user to sign in.
Request resources: Your app asks for access with scopes that you specify while setting up authentication.
Ask for consent: If your app is authenticating as a user, Google displays an OAuth consent screen so the user can decide whether to grant your app access to the requested data. Authentication with a service account doesn't require user consent.
Send approved request for resources: If the user consents to the authorization scopes, your app bundles the credentials and the user-approved scopes into a request. The request is sent to the Google authorization server to obtain an access token.
Google returns an access token: The access token contains a list of granted scopes. If the returned list of scopes is more restrictive than the requested scopes, your app turns off any features limited by the token.
Access requested resources: Your app uses the access token from Google to invoke the Chat API and access Chat API resources.
Get a refresh token (optional): If your app must access the Google Chat API beyond the lifetime of a single access token, it can get a refresh token. For more information, see Use OAuth 2.0 to access Google APIs.
Request more resources: If your app needs more access, it asks the user to grant new scopes, resulting in a new request to get an access token (steps 3-6).
When Chat apps require authentication
Chat apps can send messages in response to a user interaction, or asynchronously. They can also complete tasks on a user's behalf, such as creating a Chat space or getting a list of people in a Chat space.
Chat apps don't require authentication to respond to a user interaction, unless the Chat app calls the Chat API or another Google API while processing a response.
To send asynchronous messages or perform tasks on a user's behalf, Chat apps make RESTful requests to the Chat API, which require authentication and authorization.
Responses to user interactions don't require authentication
Google Chat apps don't need to authenticate as a user or Chat app to receive and respond synchronously to interaction events.
Google Chat apps receive interaction events whenever a user interacts or invokes a Chat app, including the following:
- A user sends a message to a Chat app.
- A user @mentions a Chat app.
- A user invokes one of the Chat app's slash commands.
The following diagram shows a request-response sequence between a Chat user and Chat app:
- The user sends a message to the Chat app in Google Chat.
- Google Chat forwards the message to the app.
- The app receives the message, processes it, and returns a response to Google Chat.
- Google Chat renders the response for the user, or in a space.
This sequence repeats for each Chat app interaction event.
Asynchronous messages require authentication
Asynchronous messages occur when a Chat app makes a request to the Chat API, which requires authentication and authorization.
By calling the Chat API, Chat apps can post messages to Google Chat or complete tasks and access data on a user's behalf. For example, after detecting a server outage, a Chat app can call the Chat API to:
- Create a Chat space dedicated to investigating and fixing the outage.
- Add people to the Chat space.
- Post a message to the Chat space to give details about the outage.
The following diagram shows an asynchronous message sequence between a Chat app and a Chat space:
- A Chat app creates a message by calling the
Chat API using the
spaces.messages.createmethod, and includes user credentials in the HTTP request. - Google Chat authenticates the Chat app with service account or user credentials.
- Google Chat renders the app's message to a specified Chat space.
Chat API scopes
Configure your app's OAuth consent screen and choose scopes to define what information is displayed to users and app reviewers, and register your app so that you can publish it later.
To define the level of access granted to your app, you need to identify and declare authorization scopes. An authorization scope is an OAuth 2.0 URI string that contains the Google Workspace app name, what kind of data it accesses, and the level of access.
Non-sensitive scopes
| Scope code | Description |
|---|---|
https://www.googleapis.com/auth/chat.bot
|
Lets Chat apps view chats and send messages. Gives access to all features available to Chat apps. |
Sensitive scopes
| Scope code | Description |
|---|---|
https://www.googleapis.com/auth/chat.spaces
|
Create conversations and spaces and view or update metadata (including history settings) in Chat. |
https://www.googleapis.com/auth/chat.spaces.create
|
Create new conversations in Chat. |
https://www.googleapis.com/auth/chat.spaces.readonly
|
View chat and spaces in Chat. |
https://www.googleapis.com/auth/chat.memberships
|
View, add, and remove members from conversations in Chat. |
https://www.googleapis.com/auth/chat.memberships.app
|
Add and remove itself from conversations in Google Chat. |
https://www.googleapis.com/auth/chat.memberships.readonly
|
View members in Chat conversations. |
https://www.googleapis.com/auth/chat.messages.create
|
Compose and send messages in Chat. |
https://www.googleapis.com/auth/chat.messages.reactions
|
View, add, and delete reactions to messages in Chat. |
https://www.googleapis.com/auth/chat.messages.reactions.create
|
Add reactions to a message in Chat. |
https://www.googleapis.com/auth/chat.messages.reactions.readonly
|
View reactions to a message in Chat. |
Restricted scopes
| Scope code | Description |
|---|---|
https://www.googleapis.com/auth/chat.delete
|
Delete conversations and spaces, and remove access to associated files in Chat. |
https://www.googleapis.com/auth/chat.messages
|
View, compose, send, update, and delete messages, and add, view, and delete reactions to messages. |
https://www.googleapis.com/auth/chat.messages.readonly
|
View messages and reactions in Chat. |
The scopes in the preceding tables indicate their sensitivity, according to the following definitions:
Non-sensitive—These scopes provide the smallest sphere of authorization access and only require basic app verification. For information about this requirement, see Steps to prepare for verification.
Sensitive—These scopes provide your app access to a specific user's Google data after receiving authorization from the user. It requires you to go through additional app verification. For information about this requirement, see Steps for apps requesting sensitive scopes.
Restricted—These scopes provide wide access to Google user data and require you to go through the restricted scope verification process. For information about this requirement, see Google API Services: User Data Policy and Additional Requirements for Specific API Scopes. See also Steps for apps requesting restricted scopes.
If your app requires access to any other Google APIs, you can add those scopes as well. For more information about Google API scopes, see Using OAuth 2.0 to Access Google APIs.
To learn more about scopes for Google Workspace APIs, see Configure the OAuth consent screen and choose scopes.
Types of required authentication
There are two ways Chat apps can authenticate and authorize with the Chat API: user credentials or service accounts.
With user credential authorization, a Chat app can access user data and complete actions on a user's behalf. OAuth scopes specify the authorized data and actions. However, these Chat apps can't be published publicly. For more information, see Publish Google Chat apps.
With app authorization, a Chat app accesses
the API as an app using service account credentials. App authorization always
uses the chat.bot authorization scope.
If you're a domain administrator, you can grant domain-wide delegation of authority to authorize an application's service account to access your users' data without requiring each user to give consent. After you configure domain-wide delegation, you can make API calls using your service account to impersonate a user account. Although a service account is used for authentication, domain-wide delegation impersonates a user and is therefore considered user authentication. Any functionality that requires user authentication, can use domain-wide delegation.
When deciding which type of credential to use for a particular API request, keep in mind that some API methods only support a particular type of credential. If an API method supports both credentials, the type of credential used in the call affects the result that is returned:
- With app authorization, the methods only return resources that the app can access.
- With user authorization, the methods only return resources that the user can access in the Chat UI.
For example, calling the ListSpaces method with app authorization returns the
list of spaces that the app is a member of. Calling the ListSpaces with user
authorization returns the list of spaces that the user is a member of. In
practice, your app might use both types of authorization when calling the
Chat API, depending on the functionality that you want.
For asynchronous Chat API calls
The following table lists the Chat API methods and their supported authorization scopes:
| Method | User authentication supported | App authentication supported | Authorization scopes supported | |
|---|---|---|---|---|
| Spaces | ||||
| Create a space | — |
|
||
| Set up a space | — |
|
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| Get a space |
With User authentication:
|
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| List spaces |
With User authentication:
|
|||
| Update a space | — |
|
||
| Delete a space | — |
|
||
| Find a direct message |
With User authentication:
|
|||
| Members | ||||
| Create a member | — |
|
||
| Get a member |
With User authentication:
|
|||
| List members |
With User authentication:
|
|||
| Delete a member | — |
|
||
| Messages | ||||
| Create a message |
With User authentication:
|
|||
| Get a message |
With User authentication:
|
|||
| List messages | — |
|
||
| Update a message |
With User authentication:
|
|||
| Delete a message |
With User authentication:
|
|||
| Reactions | ||||
| Create a reaction | — |
|
||
| List reactions | — |
|
||
| Delete a reaction | — |
|
||
| Media & attachments | ||||
| Upload media as a file attachment | — |
|
||
| Download media |
With User authentication:
|
|||
| Get a message attachment | — |
|
||
For Chat app interaction events
The following table lists common ways that users interact with Chat apps and whether authentication is required or supported:
| Scenario | No authentication required | User authentication supported | App authentication supported | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Receive messages from: |
|
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| Respond to messages: |
|
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| Send new messages: |
|
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Related topics
- For an overview of authentication and authorization in Google Workspace, see Learn about authentication & authorization.
- For an overview of authentication and authorization in Google Cloud, see Authentication overview.
- To learn more about service accounts, see Service accounts.
- To learn more about how Google APIs leverage OAuth 2.0, see Using OAuth 2.0 to Access Google APIs.
- Set up authentication and authorization with user credentials or a service account.