Generate Feide secret C#

generate.cs

// Jeg fikk det til å virke først når jeg konverterte pem sertifikatet til XML for import til RSA. 
// Sånn sett kunne det sikkert ha vært interessant for andre og ha dette tilgjengelig. 
// Xml er vedlagt
 
// Jose-jwt from https://github.com/dvsekhvalnov/jose-jwt
using Jose;
using System.Text;
using System.Security.Cryptography;
using System.Runtime.InteropServices;
 
public string Generate_feidesecret(string key)
{
    string FeideSecret = null;
    string FeidePublicCertAsXML = "<RSAKeyValue><Modulus>!!REPLACE_WITH_MODULUS_VALUE_FROM_XML!!</Modulus><Exponent>!!REPLACE_WITH_EXPONENT_VALUE_FOM_XML!!</Exponent></RSAKeyValue>";
 
    RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
    RSA.FromXmlString(FeidePublicCertAsXML);
    var payload = new Dictionary<string, object>()
        {
            { "secret", GenerateBase32Key(16) }
        };
    var jsonpay = JsonConvert.SerializeObject(payload);
 
    FeideSecret = JWT.Encode(jsonpay, RSA, JweAlgorithm.RSA_OAEP, JweEncryption.A128CBC_HS256);
 
    return FeideSecret;
}
 
public string GenerateBase32Key(int length)
{
    string def = "ABCDEFGHJKLMNOPQRSTUVWXYZ234567";
    Random rnd = new Random();
    StringBuilder ret = new StringBuilder();
    for (int i = 0; i < length -1; i++)
        ret.Append(def.Substring(rnd.Next(def.Length), 1));
    string Base32Key = ret.ToString();
    return Base32Key;
}

RSAKey_feide2factorPublicKey.xml

<RSAKeyValue>
  <Modulus>up7WiUltl3/etJmKC+y8Nv1+8qDZMmB4jy4/m2iYHy/2oTWp2ghAVO+voiDx1rhAWEckc15ZhctOTS8APIIOoMLujFPOes1Hm0tj3LWhwM0vxCKEnb303oaXPHHtbrpbohnjEHg7tOgVK1mEm4MQoUfhnolK9ZrWERd+koLXvs18HfFCE+MMTlsEIEDfgprVVndxNtQMqYcDpfkDGgLkMEhtj+3Ae38kYnUVHPNWHXIm2sDYDyImBZhoF7ire45oLl718ZNLBbBdvgwQ2ZP7HWSnWgcInc+NoE6dMXN5IGdIwEUDm+eNBtasKHihGeDZXbkvbIg6VJmRY8VbQQCvJw==</Modulus>
  <Exponent>AQAB</Exponent>
</RSAKeyValue>