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https://github.com/jitbit/AspNetSaml

Very simple SAML 2.0 consumer module for ASP.NET/C#
https://github.com/jitbit/AspNetSaml

asp-net asp-net-core asp-net-mvc aspnetcore dotnet saml saml-service-provider saml2 single-sign-on sso

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Very simple SAML 2.0 consumer module for ASP.NET/C#

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# AspNetSaml



Very short and simple SAML 2.0 "consumer" implementation in C#.



It's a *SAML client* library, not a *SAML server*. As in - allows adding SAML single-sign-on to your ASP.NET app, but *not* to provide auth services to other apps. In other words, it's a library for "service-providers" not for "identity providers".



## Installation



`Install-Package AspNetSaml`



Adds a very small .NET Standard 2.0 library (11KB dll) that works with both ASP.NET Core and the "old" ASP.NET Framework. Please refer to [releases](https://github.com/jitbit/AspNetSaml/releases) for the change log.



# Usage



## How SAML works? (please read this)



SAML workflow has 2 steps:



1. User is redirected to the SAML provider (with some magic in the query-string) where he authenticates

2. User is redirected back to your app, where you validate the payload



Here's how you do it (this example is for ASP.NET Core MVC):



## 1. Redirecting the user to the saml provider:



```c#

//this example is an ASP.NET Core MVC action method

public IActionResult Login()

{

	//TODO: specify the SAML provider url here, aka "Endpoint"

	var samlEndpoint = "http://saml-provider-that-we-use.com/login/";



	var request = new AuthRequest(

		"http://www.myapp.com", //TODO: put your app's "entity ID" here

		"http://www.myapp.com/SamlConsume" //TODO: put Assertion Consumer URL (where the provider should redirect users after authenticating)

	);



	//now send the user to the SAML provider

	return Redirect(request.GetRedirectUrl(samlEndpoint));

}

```



## 2. User has been redirected back



User is sent back to your app - you need to validate the SAML response ("assertion") that you recieved via POST.



Here's an example of how you do it in ASP.NET Core MVC



```c#

//ASP.NET Core MVC action method... But you can easily modify the code for old .NET Framework, Web-forms etc.

public async Task SamlConsume()

{

	// 1. TODO: specify the certificate that your SAML provider gave you

	string samlCertificate = @"-----BEGIN CERTIFICATE-----

BLAHBLAHBLAHBLAHBLAHBLAHBLAHBLAHBLAHBLAHBLAHBLAH123543==

-----END CERTIFICATE-----";



	// 2. Let's read the data - SAML providers usually POST it into the "SAMLResponse" var

	var samlResponse = new Response(samlCertificate, Request.Form["SAMLResponse"]);



	// 3. DONE!

	if (samlResponse.IsValid()) //all good?

	{

		//WOOHOO!!! the user is logged in

		var username = samlResponse.GetNameID(); //let's get the username

		

		//the user has been authenticated

		//now call context.SignInAsync() for ASP.NET Core

		//or call FormsAuthentication.SetAuthCookie() for .NET Framework

		//or do something else, like set a cookie or something...

		

		//FOR EXAMPLE this is how you sign-in a user in ASP.NET Core 3,5,6,7

		await context.SignInAsync(new ClaimsPrincipal(

			new ClaimsIdentity(

				new[] { new Claim(ClaimTypes.Name, username) },

				CookieAuthenticationDefaults.AuthenticationScheme)));

		

		return Redirect("~/");

	}

	

	return Content("Unauthorized");

}

```



# Bonus: reading more attributes from the provider



SAML providers usually send more data with their response: username, first/last names etc. Here's how to get it:



```c#

if (samlResponse.IsValid())

{

	//WOOHOO!!! user is logged in



	//Some more optional stuff

	//let's extract username/firstname etc

	try

	{

		var username = samlResponse.GetNameID();

		var email = samlResponse.GetEmail();

		var firstname = samlResponse.GetFirstName();

		var lastname = samlResponse.GetLastName();

		

		//or read some custom-named data that you know the IdP sends

		var officeLocation = samlResponse.GetCustomAttribute("OfficeAddress");

	}

	catch (Exception ex)

	{

		//insert error handling code

		//in case some extra attributes are not present in XML, for example

		return null;

	}

}

```



# Notes about the source code



All the functionality sits in one single short file [Saml.cs](https://github.com/jitbit/AspNetSaml/blob/master/AspNetSaml/Saml.cs) other stuff in this repo are just unit tests, nuget-packaging etc. You can take that file and throw it in your project, it should work just fine.



P.S. This library has been battle-tested for years in production in our [helpdesk app](https://www.jitbit.com/helpdesk/) please check it out if you're looking for a ticketing system for your team. Cheers.