I need some advice on some logic used in regards to encryption and encoding. I have the following string which is an encryption version of something:

dMXGnuRmZuestTpYPt55QwPELPaNd7hb4s6Ceu89hvgU2wP44BQj+FALWLMa+KNSJRlRpnmopIIvuHo9dtuK0Q==

This string is passed in a URL as a Session variable. So, basically, the URL may look like this:

MyPage.aspx?Session=dMXGnuRmZuestTpYPt55QwPELPaNd7hb4s6Ceu89hvgU2wP44BQj+FALWLMa+KNSJRlRpnmopIIvuHo9dtuK0Q==

When the page is processed, I am getting this session variable by the use of oRequest.QueryString("Session"). However, as this is a Url, the browser has applied some encoding to it. So, what I received on the server side, when using that syntax, is the encoding version and not the original string. This causes a problem as there is no way to know if the + signs, for example, were there before the encoding or not. If there were there before the encoding, then I have a problem as I cannot decrypt that back because this is not the original string I used.

Is there a way to resolve that issue?