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
        }