using AES Enhanced for encrypting query string

Hi.

I'm using AES Enhanced for encrypting query string that needs to be secure.

There is a small problem I am experiencing with this that once the query string is encrypted it has the occasional + character in the string which the request.querystring does not capture but sees as a blank space. I also wonder if there could be other characters presented by AES that the request.querystring method would not agree with.

e.g.

get-value.aspx?mystring=ab+c

will be captured from the request.querystring as "ab c" (ab space c)

Is there some simple approach to capture the query string in raw form? 

Is the + character the only non compliant character the AES uses? If this is the case I could imaginably just do a replace before and after sending it with a temporary substitute character but I do wonder if AES will drop any other characters in?

Does anyone have any ideas on this, perhaps there is a far be ...