In the modern digital workspace, seamless user authentication is essential for enhancing productivity and user experience. One way to achieve this in Microsoft 365 is by implementing Single Sign-On (SSO) in your Outlook add-ins. This guide will walk you through the steps to authenticate a user using an SSO token in an Outlook add-in.
Why Use SSO in Outlook Add-ins?
SSO simplifies the authentication process by allowing users to log in once and access multiple applications without the need to re-enter credentials. This not only improves security but also reduces friction for end users, providing a smooth, integrated experience in the Microsoft 365 ecosystem.
Step-by-Step Guide to Implementing SSO in Outlook Add-ins
1. Enable Modern Authentication
Modern authentication is the foundation for enabling SSO in Microsoft 365. To check if it’s enabled for your organization, follow Microsoft's guide on modern authentication.
2. Register Your Add-in in Azure Active Directory (Azure AD)
To use SSO, your add-in must be registered in Azure AD. This involves:
- Creating an application registration in the Azure portal.
- Setting up permissions for Microsoft Graph or other APIs you want to access.
Visit Register an Office Add-in with Azure AD for a detailed tutorial.
3. Configure Your Add-in Manifest
Modify your add-in manifest file to include the WebApplicationInfo element. This element contains your Azure AD application ID and resource details, linking your add-in to the registered app in Azure AD. Here’s an example snippet:
<WebApplicationInfo>
<Id>your-client-id</Id>
<Resource>api://your-resource-id</Resource>
<Scopes>
<Scope>https://graph.microsoft.com/User.Read</Scope>
</Scopes>
</WebApplicationInfo>
For more information, see the manifest configuration guide.
4. Use OfficeRuntime.auth.getAccessToken to Obtain the SSO Token
In your add-in's JavaScript code, use the OfficeRuntime.auth.getAccessToken method to retrieve the SSO token. Here’s how:
Office.onReady(function(info) {
if (info.host === Office.HostType.Outlook) {
OfficeRuntime.auth.getAccessToken({ allowSignInPrompt: true })
.then(function(token) {
console.log("Access token retrieved:", token);
// Use the token for further authentication
})
.catch(function(error) {
console.error("Error retrieving access token:", error);
});
}
});
This method handles user authentication and fetches the SSO token. If users are not signed in, they’ll be prompted to log in.
5. Validate and Exchange the Token
Once you obtain the SSO token, validate it on your server to authenticate the user. If you need to access Microsoft Graph or other APIs, exchange the token for an access token specific to those services. Refer to Authorize to Microsoft Graph with SSO for implementation details.
Fallback Authentication for Older Versions
Not all environments support SSO. For example, older versions of Office might lack modern authentication capabilities. In these cases, implement a fallback mechanism, such as using an Exchange identity token or prompting the user for credentials. Learn more in the fallback authentication guide.
Benefits of Implementing SSO in Outlook Add-ins
- Enhanced User Experience: Users log in once and gain access to all integrated applications.
- Increased Security: Reduces password fatigue and supports stronger authentication mechanisms.
- Improved Productivity: Simplifies workflows, allowing users to focus on tasks rather than login procedures.
By integrating SSO in your Outlook add-in, you can provide a secure, user-friendly experience that aligns with modern workplace expectations. With Azure AD registration, modern authentication, and proper token handling, your add-in can leverage the full potential of the Microsoft 365 ecosystem.
For more detailed technical guidance, visit Microsoft's official documentation.
