How to generate JWT Token with C# - Hello World version ( jwt.io )

Program.cs

using System;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Microsoft.IdentityModel.Tokens;


namespace ConsoleApp3
{
    class Program
    {
        
        public static string buildJwtToken(string base64Key)
        {
            var tokenHandler = new JwtSecurityTokenHandler();
            var now = DateTime.UtcNow;
            var securityKey = Convert.FromBase64String(base64Key);
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new[]
                {
                    new Claim( "sub","Example", ClaimValueTypes.String, "example" )
                }),
                Issuer = "example",
                Audience = "https://www.example.com",
                Expires = now.AddMinutes(3),
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(securityKey), 
                    SecurityAlgorithms.HmacSha256),
            };

            var token = tokenHandler.CreateToken(tokenDescriptor);
            var tokenString = tokenHandler.WriteToken(token);

            return tokenString;
        }
        
        static void Main(string[] args)
        {
            Console.WriteLine("version: Hello World!");
            var base64Key = "MWNhMzA4ZGY2Y2RiMGE4YmY0MGQ1OWJlMmExN2VhYzE=";
            Console.WriteLine(buildJwtToken(base64Key));
            Console.WriteLine("base64 key " + base64Key);
            Console.WriteLine(Encoding.ASCII.GetString(Convert.FromBase64String(base64Key)));
        }
    }
}