Api Key authentication handler

gistfile1.cs

    public class ApiKeyAuthHandler : DelegatingHandler
    {
        private const string ApiKeySchemeName = "ApiKey";
        private const string AuthResponseHeader = "WWW-Authenticate";
        
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            var authHeader = request.Headers.Authorization;

            if (authHeader != null && authHeader.Scheme == ApiKeySchemeName)
            {
                var principal = ValidateApiKey(authHeader.Parameter);

                if (principal != null) 
                {
                    Thread.CurrentPrincipal = principal;
                }
            }

            return base.SendAsync(request, cancellationToken)
                .ContinueWith(task =>
                {
                    var response = task.Result;

                    if (response.StatusCode == HttpStatusCode.Unauthorized && !response.Headers.Contains(AuthResponseHeader))
                    {
                        response.Headers.Add(AuthResponseHeader, ApiKeySchemeName);
                    }

                    return response;
                });
        }


        IPrincipal ValidateApiKey(string authParameter)
        {
            if (authParameter.IsNullOrEmpty() || authParameter != "1234-5678")
            {
                return null;
            }
            
            return new GenericPrincipal(new GenericIdentity("Test User", ApiKeySchemeName), null);
        }
    }

You will probably change that when you put this in your app but you reach out to the Result of the Task object before checking status of it. The operation might have been faulted or cancelled.