[Migration] Support sharing auth state with "backend" System.Web app

[pranavkm]

As part of #40078, we'll need to determine a way to share auth state between the front end .NET Core, and backend System.Web app. Prelimnary work here is to determine the list of authorization providers (cookie, token etc) that we need to support based on how frequently they appear in user apps.

[Tratcher]

Possible kinds of auth (not necessarily the ones people need):

• JWT/Bearer/Basic/Digest/API - Easy, implement in both apps separately.
• Cookie/Forms/Owin - Requires shared formats and encryption
• Identity - Depends on cookie auth, requires a shared database
• OAuth, OpenIdConnect, AzureAd, B2C - Depends on Cookie Auth, and where you want to put the login page.
• Windows/Negotiate/NTLM/Kerberos - Would need to be handled by the front end, doesn't proxy well. Could be converted to something else like JWT for the backend. We do something more complex for IIS out-of-proc, (duplicate handles) but I think that only works because IIS started the other process.

[Tratcher]

So far I've seen reports from potential migration customers that are currently using:

• JWT
• OWIN Cookies & OpenIdConnect
• B2C

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 7 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[adityamandaleeka]

Closing since this is done as part of https://devblogs.microsoft.com/dotnet/incremental-asp-net-migration-tooling-preview-2/

Further requests in this area can be filed over on https://github.com/dotnet/systemweb-adapters/