using System;

using System.Collections.Generic;

using System.IdentityModel.Tokens.Jwt;

using System.Security.Claims;

using System.Text;

using Microsoft.IdentityModel.Tokens;

using System.Collections.Generic;

using System.Text.Json;

​

public class Program

{

    public static void Main()

    {

        String secretKey = "SECRETKEY_IS_VERY_LONGGGGGGGGGGGGGGGGGGGGGGGG";

        String userId = "xxxxxxxx";

        String token = genToken(userId,secretKey);

        Console.WriteLine(token);

        var json = ValidateJwtTokenToJson(token,secretKey);

        if(json != null) {

            Console.WriteLine(json);

        }

    }

    public static String genToken(String userId,String secretKey) {

        int expireMinutes = 60;

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

        var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

​

        var claims = new[]

        {

            new Claim("userId", userId),

            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())

        };

         var token = new JwtSecurityToken(

            issuer: "APP_NAME",

            audience: "APP_USER",

            claims: claims,

            expires: DateTime.UtcNow.AddMinutes(expireMinutes),

            signingCredentials: credentials

        );

        return new JwtSecurityTokenHandler().WriteToken(token);

    }

    public static string? ValidateJwtTokenToJson(string token, string secretKey)

    {

        var tokenHandler = new JwtSecurityTokenHandler();

        var key = Encoding.UTF8.GetBytes(secretKey);

​

        var validationParameters = new TokenValidationParameters

        {

            ValidateIssuerSigningKey = true,

            IssuerSigningKey = new SymmetricSecurityKey(key),

            ValidateIssuer = false,

            ValidateAudience = false,

            ClockSkew = TimeSpan.Zero

        };

​

        try

        {

            var principal = tokenHandler.ValidateToken(token, validationParameters, out SecurityToken validatedToken);

​

            if (validatedToken is JwtSecurityToken jwtToken &&

                jwtToken.Header.Alg.Equals(SecurityAlgorithms.HmacSha256, StringComparison.InvariantCultureIgnoreCase))

            {

                var claimsDict = new Dictionary<string, string>();

                foreach (var claim in principal.Claims)

                {

                    claimsDict[claim.Type] = claim.Value;

                }

                return JsonSerializer.Serialize(claimsDict, new JsonSerializerOptions { WriteIndented = true });

            }

​

            return null;

        }

        catch

        {

            return null;

        }

    }

}