using System;

using System.ComponentModel.DataAnnotations;

using Microsoft.AspNetCore.Builder;

using Microsoft.AspNetCore.Http;

using Microsoft.Extensions.Hosting;

using System.Collections.Generic;

using System.Linq;

using Microsoft.Extensions.DependencyInjection;

using System.Security.Claims;

using System.Text;

using Microsoft.IdentityModel.Tokens;

using System.IdentityModel.Tokens.Jwt;

using Microsoft.AspNetCore.Authentication.JwtBearer;

using Microsoft.AspNetCore.Authorization;

public class Program

{

    public static void Main()

    {

        var svc = new TokenService();

        var res = svc.BuildToken("keykeykeykeykeykeykeykey", "issuer");

        Console.WriteLine(res);

    }

}

​

public class TokenService

{

    private TimeSpan ExpiryDuration = new TimeSpan(0, 30, 0);

    public string BuildToken(string key, string issuer)

    {

        var claims = new[]

        {

                new Claim(ClaimTypes.Name, "Agnostics"),

                new Claim(ClaimTypes.NameIdentifier,

                Guid.NewGuid().ToString())

             };

        var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(key));

        var credentials = new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256Signature);

        var tokenDescriptor = new JwtSecurityToken(issuer, issuer, claims,

            expires: DateTime.Now.Add(ExpiryDuration), signingCredentials: credentials);

        return new JwtSecurityTokenHandler().WriteToken(tokenDescriptor);

    }

}