I  implementing Rijndael in my Web application, but in some PC send error message when trying to decrypt the chain: "Invalid to character in a Base-64 String", I read some news about it and say that the problem is because the string contains characters like " +" in my encrypted chain. Exists some way to encrypt my string without symbols like "+"?  The problem only apear in Internet Explorer, I try with other browsers like Avant and Firefox and works very good.

 Thanks for any help.