Integrate ASP.NET Core Identity With Microsoft.Identity.Web in Blazor for Authentication - authentication

Question

I have been working on authentication methods for my blazor app for some time now. I am currently developing as a standalone protected WebApi + Blazor Server, but will ultimately migrate to standalone protected WebApi + Hosted Blazor WASM so I need to be mindful of both server and client side authentication. The WebAPI will also serve an external OData feed and API for end users that also needs to be protected using the central authentication mechanism.
I would like to be able to sign on with Microsoft (ie. Microsoft.Identity.Web / MSAL), but want to configure some fairly complex roles and behaviours at the database level
(ie. ASP.NET Core Identity). To hopefully help someone else understand the different documentation sets, following are links to MS docs for the 2 options.
Introduction to Identity on ASP.NET Core
Microsoft Identity Platform Documentation
Don’t know about anyone else, but I have found it very difficult to navigate through the different documentation sets and tutorials to firstly understand how they work and secondly determine if it is best for me.
My question is, does anyone have any documentation on how they have integrated Microsoft.Identity.Web with the individual user accounts available in ASP.NET Core Identity for Blazor Server and/or WASM apps?, .
The following link shows how to do it all within ASP.NET Core Identity.
Integrate ASP.NET Core Identity with Microsoft account | BinaryIntellect Knowledge Base
If I was building an MVC web app, that’s what I would do. However, I really like the token handling capabilities of Microsoft.Identity.Web / MSAL (ie. ITokenAquisition etc.) for Blazor. It seems to be a real kludge to have to use the Razor pages for ASP.NET Core Identity and handling tokens securely becomes an issue – especially for Blazor WASM.
Chris Sainty has done some good work in porting some of the ASP.Net Razor pages to Blazor Components in the following link. However he does a lot of (very clever) manual processing of the token and I’m not sure I like the idea of storing the token in unprotected Local Storage of the blazor app. I haven’t gone into it in full detail yet, but I don’t think this method will be directly transferrable to Blazor WASM.
Authentication with client-side Blazor using WebAPI and ASP.NET Core Identity (chrissainty.com)
This SO post indicates that it is not possible to integrate Individual user accounts with Microsoft.Identity.Web.
c# - Microsoft Identity Plataform with asp.net Core Identity - Stack Overflow
I got a working solution going where I had both ASP.NET Core Identity and Microsoft.Identity.Web working side by side. However, I found this to be very difficult to implement and debug. Once you start mixing the various builder.Services.AddAuthetication(
) options (eg. .AddMicrosoftIdentityWebApp, . AddMicrosoftIdentityWebApi, .AddIdentityCore, .AddIdentity, .AddDefaultIdentity, .AddJWTBearer etc. etc.) I have found that you enter a world of pain and unpredictable behaviour. I basically had to go back to the source for each of them to work out what they were actually doing under the covers and work out how to blend them. I ended up going back to the raw OAuth / OpenId specifications and implementing everything manually – which is very unsatisfactory and I was unhappy with the risk I was taking in potentially introducing a security flaw – even though I got it to “work”.
EDIT: This SO post is similar to what I implemented. Microsoft Identity Local User Accounts and MSAL
I can’t believe how hard it has been to just get to this level of understanding, and still not have a solid working concept that does what I want it to do that is supported by documented acceptable techniques and not just my kludge at implementing everything manually.
Right now it appears to me that if I want to use as much out of the box / documented functionality as possible, I suspect that I should use ASP.NET Core Identity and work out how to integrate the ASP.net razor pages into my Web Api, Blazor Server and and Blazor WASM apps. However, this appears to be a backward step since Microsoft.Identity.Web / MSAL seems to be so much better suited to Blazor and seems to be the direction that MS is going.
If anyone can point me to some current examples of how this can be done, I would be very thankful.

Answer 1

I think I have found at least a partial answer to my question. The key problem I faced was how to capture the callback event from Microsoft.Identity.Web so that I can persist / retrieve info to/from the database during the authentication event. I was hung up on the ASP.NET Core Identity method of doing that.
I found the following SO post that provides information on how to respond to the OnTokenValidated event using Microsoft.Identity.Web. Microsoft.Identity.Web: OnTokenValidated event not triggered
Having access to this event means that I will be able to implement what I need to do at the database level and move on.