Middlaware authentication for Web Api allowanonymous method

Question

I have a middle ware class as below and expecting token for allow-anonymous method. Can some suggest me what am i missing over here.

 

Middleware class as follows :

 namespace filetrs
 {
     public class TestingAuthenticationFilter : IAuthenticationFilter
      {
             public async Task AuthenticateAsync(HttpAuthenticationContext context, CancellationToken cancellationToken)
               {
                 var alias = GetAliasFromJwt(context.Request.Headers.Authorization.ToString());
                   await Task.Yield();
                }
    public Task ChallengeAsync(HttpAuthenticationChallengeContext context, CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }
    public static string GetAliasFromJwt(string jwt)
    {
        string alias, extractedToken;
        alias = extractedToken = string.Empty; string tokenTypeToRemove = "Bearer ";
        if (tokenTypeToRemove.Length > 0)
        {
            extractedToken = jwt.Substring(tokenTypeToRemove.Length);
            var handler = new JwtSecurityTokenHandler();
            var jwtSecurityToken = handler.ReadToken(extractedToken) as JwtSecurityToken;
            alias = jwtSecurityToken.Claims.First(claim => claim.Type == "abc").Value.Split('@').First();
        }
        return alias;
    }
}

Please find APi class as well

 public static class WebApiConfig
 {
 public static void Register(HttpConfiguration config)
 { //var cors = new EnableCorsAttribute("*", "*", "*");
 //config.EnableCors(cors);
       config.MapHttpAttributeRoutes();
        config.Routes.MapHttpRoute(
        name: "DefaultApi",
   routeTemplate: "api/{controller}/{id}",
           defaults: new { id = RouteParameter.Optional } );
   config.Filters.Add(new TestingAuthenticationFilter());
  config.Filters.Add(new ExceptionHandlingAttribute());
}}

ConfigAuth method from startup.cs as follows

public void ConfigureAuth(IAppBuilder app)
{
app.UseWindowsAzureActiveDirectoryBearerAuthentication
( new WindowsAzureActiveDirectoryBearerAuthenticationOptions
{ Tenant = tenant, TokenValidationParameters = new TokenValidationParameters { ValidAudience = clientId }
});

I am unable to find the solution. Please someone help me on this?