string FName = NameReader["doc_data_name"].ToString();
byte[] ContentBytes = System.Text.Encoding.UTF8.GetBytes(FName);
byte[] b = (new SHA256Managed().ComputeHash(ContentBytes));
      StringBuilder Hex = new StringBuilder(b.Length * 2);
                                      foreach (byte bit in b)
                                        {
                                            if (bit.ToString("x").Length == 1)
                                            {
                                                Hex.Append("0" + bit.ToString("x"));
                                            }
                                            else
                                            {
                                                Hex.Append(bit.ToString("x"));
                                            }
                                        }                                        

                                        string key = Hex.ToString().ToLower();

   byte[] ContentBytes = System.Text.Encoding.GetEncoding(1251).GetBytes(FName);
   byte[] ContentBytes = System.Text.Encoding.Unicode.GetBytes(FName);