using System;

using System.IdentityModel.Tokens.Jwt;

using Microsoft.IdentityModel.Tokens;

​

public class Program

{

    public static void Main() {

        var token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9." +

            "eyJzdWIiOiIxIiwibmJmIjoxNjQwMTE2NTIyLCJleHAiOjE2NDAyODkzMjIsImlhdCI6MTY0MDExNjUyMiwiaXNzIjoiZGV2Lm" +

            "RjLnJzdWl0ZWJhY2tzdGFnZS5jb20iLCJhdWQiOiJkZXYuY3BxLnJzdWl0ZWJhY2tzdGFnZS5jb20ifQ." +

            "6PTWGbMEV8cGjn81IqRXKG12dlaR7o7m1kr4krct2F8";

        var secret = "QPbBCOiEBaThao3tUZInPsvXY8cbfuA19oP8UIXsckk=";

        var tokenHandler = new JwtSecurityTokenHandler();

        var key = new SymmetricSecurityKey(Convert.FromBase64String(secret));

        var validationParameters = new TokenValidationParameters() {

            ValidateIssuerSigningKey = true,

            IssuerSigningKey = key

        };

​

        try {

            SecurityToken securityToken;

            tokenHandler.ValidateToken(token, validationParameters, out securityToken);

            Console.WriteLine("Valid!");

        } catch (Exception ex) {

            Console.WriteLine(ex.Message);

            Console.WriteLine("Invalid!");

        }

    }

}