This document summarizes a webinar about integrating Azure Active Directory B2C (AAD B2C) with applications using the Microsoft Authentication Libraries (MSAL). It discusses how MSAL can be used to acquire tokens to call protected APIs and validate tokens in web APIs and applications. It provides an overview of using MSAL in .NET Core web apps to sign users in with AAD B2C, redeem authorization codes to acquire tokens, and implement token caching for silent authentication. The document demonstrates how to build a .NET Core web app that signs users in with AAD B2C using MSAL.

1. Azure AD B2C Webinar Series

2. B2C & App Integration with the
Microsoft Authentication Libraries (MSAL)
Azure AD B2C
Webinar series

7. Why MSAL?
 Supports OAuth and OIDC
 Acquires all types of tokens.
 Implements a Token Cache
 Developer Friendly API
 Battle hardened
 Get help when you need it!

8. Authentication Libraries
Microsoft Authentication Libraries (MSAL)
Used to acquire tokens to call protected APIs
Middleware libraries
Used by node.js, ASP.NET, ASP.NET Core to validate
access tokens in web APIs and ID tokens in Web apps.
Scenarios and supported platforms and language

10. AAD B2C

11. Issue a token
Read
user
profile
Create
an
account
Sign-Up
or Sign-
In

12. Policy name
Token issuing
Redirect back to application
Validate and
read token
Read user profile

13. ACTIVITY

14. ACTIVITY

15. Create an ASP .NET Core Web App
Sign-in Users

17. If you start from ASP .NET Core templates
If, now, you want to call web APIs reliably:
OnAuthorizationCodeReceived
deem the auth code
build an MSAL.NET confidential client application
mplement token cache serialize
AcquireTokenSilent

18. Override the OpenIdConnect Events

19. Build a confidential client with MSAL .NET
string authority = $"{_applicationOptions.Instance}tfp/“
+"{_microsoftIdentityOptions.Domain}/"+
"{_microsoftIdentityOptions.DefaultUserFlow}";
_application = ConfidentialClientApplicationBuilder
.CreateWithApplicationOptions(_applicationOptions)
.WithRedirectUri(currentUri)
.WithB2CAuthority(authority)
.WithHttpClientFactory(_httpClientFactory)
.Build();

20. Redeem the auth code with MSAL .NET

21. Implement token cache serialization
• Complex (security and performance implications)
• Serialization depends
on your needs
- in memory,
- database,
- Redis etc …

22. In the Controller, acquire a token with MSAL .NET

23. Building blocks and integration points
ASP.NET Core Web App or Web API
ASP.NET Core framework
ASP.NET Core OIDC middleware ASP.NET Core - JwtBearer middleware
Core Components
Microsoft.IdentityModel (Wilson) WsTrust…
.NET Core

24. ACTIVITY