Rsa decryption in c#

gistfile1.txt

 public static string Decrypt(string cipherText, string privateKey)
        {
            UnicodeEncoding _encoder = new UnicodeEncoding();

            var rsa = new RSACryptoServiceProvider();
            var dataByte= Convert.FromBase64String(cipherText);
            rsa.FromXmlString(privateKey);
            var decryptedByte = rsa.Decrypt(dataByte, false);
            return _encoder.GetString(decryptedByte);
        }