public override void Serialize(Util.DataSerializer writer)
 {
     base.Serialize(writer);
     writer.WriteShort((short)Book.Count);
     foreach (var r in Book)
     {
         writer.WriteShort((short)r.Purpose);
         writer.WriteContent(r.PrivateKey);
     }
 }
 public override void Serialize(Util.DataSerializer writer)
 {
     base.Serialize(writer);
     writer.WriteContent(Key as Content);
 }