Secure 2 different web applications with one identify service - asp.net-mvc

Question

Secure 2 different web applications with one identify service
Identity Service: Thinktecture Identity Service V2
Application 1: Asp.net MVC 5 application
Application 2: Asp.net Web API application
The above Applcation 1 and Application 2 are different projects and hosted in different servers. Now my scenarios are
1. Want to secure Application 1 with Identity Service.
2. Want to secure Application 2 with Identity Service.
Use case 1: If user access Application 1 it should redirect to identity service login page, once I entered the credentials and login in to application 1, the same token allow me to access Application 2.
Use case 2: If user try to access any API from Application 2 without login into Identity service, the request should reject.

Answer 1

I found a way to do this using pure SAML tokens. The trick is you need to create a delegation account in Identity Server to allow your web app to delegate identity to a specific realm (where your service lives). Then in the web app you make a service call using the the token that the user already has to get a new token which you use to access your service.
I asked a very similar question and answered it myself here.

Answer 2

Ok. I did eactly the same thing just now. Everything required to get that done is written here. If you're using IdentityServer, you need to configure the Token Type of your RP to be JWT:
this allows you to later extract the token from your authenticated MVC 5 application (see the link above to see how to do this) and then send that token to your Web API. You then need to tell you web api to accept that token, using Microsoft's JwtSecurityTokenHandler class. This class has a ValidateToken() method which accepts 2 parameters, the first being the access token that you put into your auth headers of the requests to the Web API, and the second, the validation parameters are basically what you've defined in IdentityServer's config:
validationParams = new TokenValidationParameters
{
AllowedAudiences = _allowedAudiencesAndSigningKeys.Select(x => x.Key),
ValidIssuer = ConfigurationManager.AppSettings["IssuerIdentity"],
ValidateIssuer = true,
SigningTokens = _allowedAudiencesAndSigningKeys.Select(x => new BinarySecretSecurityToken(Convert.FromBase64String(x.Value)))
};
The Audience(s)/Realm(s) you want to allow access to, the issuer name (your Identity Server name) and the signing symmetric key(s) of the applications you have defined in Identity Server and want to grand access to. The ValidateToken() method returns an ClaimsPrincipal with a list of the claims extracted from the token. The code to do all this can be put in a message handler:
public static void Configure(HttpConfiguration config)
{
var authNConfig = new AuthenticationConfiguration();
config.MessageHandlers.Add(new MyTokenValidationHandler());
}