Hawk Authentication in Thinktecture.IdentityModel can be hooked into your ASP.NET Web API through the message handler (HawkAuthenticationHandler) or the OWIN middleware (HawkAuthenticationMiddleware). The sample here is based on a self-hosted web API (WCF channel stack) using the message handler and another self-hosted web API (OWIN host adapter) using the OWIN middleware. It is possible to use the OWIN middleware and enable Hawk authentication for your ASP.NET Web API which is hosted in IIS. Of course, you can use the message handler, which is the simplest option but we will see how message handler measures up to OWIN middleware in the case of hosting in IIS.