Web Forms :: Encrypt And Decrypt Using Data Grid

I have search all around the internet and still have not found a solution for this problem. I have successfully been able to make a data grid hyperlink and encrypt the query string coming from that link. The problem that I am having is trying to decrypt the query string. When I try to decrypt it I get an error of "Invalid character in a Base-64 string."I know this means that I have a white space or an Invalid character somewhere, but for the life of me I don't know where. Futhermore I try this same code without the datagrid and replace it with just regular textboxes that passes querystrings to the next page and the code work perfectly.