ADFS JWT validation

AsyncHelper.cs

using System;
using System.Threading;
using System.Threading.Tasks;

namespace ValidateJWT
{
    internal static class AsyncHelper
    {
        private static readonly TaskFactory TaskFactory = new TaskFactory(CancellationToken.None, TaskCreationOptions.None, 
                                                                          TaskContinuationOptions.None, TaskScheduler.Default);

        public static void RunSync(Func<Task> func)
        {
            TaskFactory.StartNew(func).Unwrap().GetAwaiter().GetResult();
        }

        public static TResult RunSync<TResult>(Func<Task<TResult>> func)
        {
            return TaskFactory.StartNew(func).Unwrap().GetAwaiter().GetResult();
        }
    }
}

Program.cs

using System;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Threading;
using Microsoft.IdentityModel.Protocols;
using Microsoft.IdentityModel.Protocols.OpenIdConnect;
using Microsoft.IdentityModel.Tokens;
using Microsoft.IdentityModel.Logging;

namespace ValidateJWT
{
    // https://www.jerriepelser.com/blog/manually-validating-rs256-jwt-dotnet/
    class Program
    {
        static void Main(string[] args)
        {
            // Set audience to your expected value

            const string issuer = "http://my-adfs/adfs/services/trust";
            const string audience = "https://localhost:44321/";        
            const string adfsWellKnown = "https://my-adfs/adfs/.well-known/openid-configuration";

            // Add your JWT here

            const string testToken = "eyJ...Reg"; // Obtain a JWT to validate and put it in here

            // https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/wiki/PII

            IdentityModelEventSource.ShowPII = true;

            try
            {
                // Download the OIDC configuration which contains the JWKS
                // NB!!: Downloading this takes time, so do not do it very time you need to validate a token, Try and do it only once in the lifetime
                //     of your application!!

                IConfigurationManager<OpenIdConnectConfiguration> configurationManager = new ConfigurationManager<OpenIdConnectConfiguration>
                    (adfsWellKnown, new OpenIdConnectConfigurationRetriever());
                OpenIdConnectConfiguration openIdConfig = AsyncHelper.RunSync(async () => await configurationManager.GetConfigurationAsync(CancellationToken.None));

                // Configure the TokenValidationParameters. Assign the SigningKeys which were downloaded from ADFS. 
                // Also set the Issuer and Audience to validate

                TokenValidationParameters validationParameters =
                    new TokenValidationParameters
                    {
                        ValidIssuer = issuer,
                        ValidAudience = audience,
                        IssuerSigningKeys = openIdConfig.SigningKeys
                    };

                // Now validate the token. If the token is not valid for any reason, an exception will be thrown by the method

                SecurityToken validatedToken;
                JwtSecurityTokenHandler handler = new JwtSecurityTokenHandler();
                var user = handler.ValidateToken(testToken, validationParameters, out validatedToken);

                Console.WriteLine($"Token is validated.\n");

                // The ValidateToken method above will return a ClaimsPrincipal. 
                // Enumerate the ClaimsPrincipal

                if (null != user)
                {
                    foreach (Claim claim in user.Claims)
                    {
                        Console.WriteLine(claim.Type + "  " + claim.Value);
                    }
                }

                // Display the JSON

                Console.WriteLine("\n" + validatedToken.ToString());

            }

            catch (Exception e)
            {
                Console.WriteLine($"Error occurred while validating token: {e.Message}");                
            }

            Console.WriteLine();
            Console.WriteLine("Press ENTER to continue...");
            Console.ReadLine();
        }
    }
}

https://medium.com/the-new-control-plane/validating-an-adfs-jwt-a47099b014b9