private Rsa GetRsa()
{
var privateKeyBytes = Convert.FromBase64String(base64PrivateKey);
var parameters = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(privateKeyBytes);
#if NETSTANDARD
return new RsaStandard(parameters);
#else
var rsaCsp = new RSACryptoServiceProvider();
rsaCsp.ImportParameters(DotNetUtilities.ToRSAParameters(parameters));
return rsaCsp;
#endif
}