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It seems like only yesterday when I setup an OWIN OAuth server to provide single-signon capabilities for all of my apps. Since that time, though, OWIN has kind of fallen to the wayside in favor of newer security mechanisms in .NET Core. However, it is possible to make an OWIN application play nice with a .NET Core application to share cookie-based authentication.

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Since the OAuth server I’ve detailed previously is using OWIN, I’ve been looking at what it will take to move it to .NET Core. The OWIN OAuth Server provides all of the Secure Token creation. This functionality is not provided with .NET Core’s native middleware.

My first thought is to integrate with IdentityServer4 or Openiddict which provide Secure Token generation and are .NET Core compatible. After some cursory information gathering, I’m putting a few research links here for later use.

https://blogs.msdn.microsoft.com/webdev/2016/10/27/bearer-token-authentication-in-asp-net-core/
https://blogs.msdn.microsoft.com/webdev/2017/01/23/asp-net-core-authentication-with-identityserver4/
https://github.com/openiddict/openiddict-core
https://www.scottbrady91.com/Identity-Server/Getting-Started-with-IdentityServer-4
http://stackoverflow.com/questions/35304038/identityserver4-register-userservice-and-get-users-from-database-in-asp-net-core

After using OWIN for months for basic OAuth authentication, it’s apparent that Microsoft is abandoning OWIN . This isn’t necessarily a bad thing. .NET Core is built on a similar structure as that which was implemented in OWIN. Essentially, we have a familiar middleware pipeline.

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My current single-sign server, that utilizes OWIN, does not store information regarding users’ identity. On the back-end, it makes LDAP queries to Active Directory to authenticate users and then makes additional LDAP queries to determine roles and authorization.

Since I’ve been playing with Azure lately, I wanted to re-tool this solution to allow toggling between a data-store for user identity information and Active Directory.

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If you recall my previous post on ASP.NET Anti-forgery configuration options, you may be familiar with the way the ASP.NET MVC AntiForgeryToken helper adds the “x-frame-options SAMEORIGIN” header to server responses. This header prevents different domains from displaying your site in an iframe. Your only option to manage this feature is to completely disable it.

An all or nothing approach to configuration is quite inflexible. Additionally, if we are using the web.config to handle our configuration, that too is pretty rigid and hard to manage.

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ASP.NET has some useful security options to prevent cross-site scripting, click hijacking, and other vulnerabilities. However, configuring these options has a few caveats.

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After creating a redistributal package for a custom OWIN AuthenticationHandler that handles logins to an internally hosted Oauth2/SSO provider, I found something a little annoying.

When OWIN detects a 401 response and the AuthenticationMode is “Active,” it doesn’t capture the URL hash from the request.

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Being able to decrypt the OWIN AuthenticationTicket can be very useful. In the cases where the cookie/tickets are shared across applications, this is especially true.

Interestingly, if you’re using OWIN for both cookie-based authentication and access tokens, the Ticket is stored in both mediums.

With that in mind, the easiest method to decrypt a ticket to access claims, etc is to simply stand up a protected Resource server with a single Api endpoint to display the contents of the ticket. Going this route, the decryption is automatically handled by OWIN with very little code. The endpoint can be accessed by a user’s browser (decrypting the cookie) or by a server passing in a Bearer token.

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