csharp.auth.jwt.cs

csharp.auth.jwt.cs

using System;
using System.IO;
using System.Security.Cryptography;
using System.IdentityModel.Tokens.Jwt;
using Microsoft.IdentityModel.Tokens;
using System.Security.Claims;

namespace Auth.Util {
  class SignToken {
    static void Main(string[] args) {

      try {
        // reading the content of a private key PEM file, PKCS8 encoded 
        string privateKeyPem = File.ReadAllText("...");

        // keeping only the payload of the key 
        privateKeyPem = privateKeyPem.Replace("-----BEGIN PRIVATE KEY-----", "");
        privateKeyPem = privateKeyPem.Replace("-----END PRIVATE KEY-----", "");

        byte[] privateKeyRaw = Convert.FromBase64String(privateKeyPem);

        // creating the RSA key 
        RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
        provider.ImportPkcs8PrivateKey(new ReadOnlySpan<byte>(privateKeyRaw), out _);
        RsaSecurityKey rsaSecurityKey = new RsaSecurityKey(provider);

        // Generating the token 
        var now = DateTime.UtcNow;

        var claims = new[] {
            new Claim(JwtRegisteredClaimNames.Sub, "YOUR_CLIENTID"),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
        };

        var handler = new JwtSecurityTokenHandler();

        var token = new JwtSecurityToken
        (
            "YOUR_CLIENTID",
            "https://AAAS_PLATFORM/idp/YOUR_TENANT/authn/token",
            claims,
            now.AddMilliseconds(-30),
            now.AddMinutes(60),
            new SigningCredentials(rsaSecurityKey, SecurityAlgorithms.RsaSha256)
        );

        // handler.WriteToken(token) returns the token ready to send to AaaS !
        Console.WriteLine( handler.WriteToken(token) );
      }

      catch (Exception e) {
          Console.WriteLine(e.ToString());
          Console.WriteLine(
               new System.Diagnostics.StackTrace().ToString()
          );
      }
    }
  }
}