I'm attempting to encode the encrypted id in the Url. Like this: http://www.calemadr.com/Membership/Welcome/9xCnCLIwzxzBuPEjqJFxC6XJdAZqQsIDqNrRUJoW6229IIeeL4eXl5n1cnYapg+N

However, it either doesn't encode correctly and I get slashes '/' in the encryption or I receive and error from IIS: The request filtering module is configured to deny a request that contains a double escape sequence.

I've tried different encodings, each fails:

• HttpUtility.HtmlEncode
• HttpUtility.UrlEncode
• HttpUtility.UrlPathEncode
• HttpUtility.UrlEncodeUnicode

Update

The problem was I when I encrypted a Guid and converted it to a base64 string it would contain unsafe url characters . Of course when I tried to navigate to a url containing unsafe characters IIS(7.5/ windows 7) would blow up. Url Encoding the base64 encrypted string would raise and error in IIS (The request filtering module is configured to deny a request that contains a double escape sequence.). I'm not sure how it detects double encoded strings but it did.

After trying the above methods to encode the base64 encrypted string. I decided to remove the base64 encoding. However this leaves the encrypted text as a byte[]. I tried UrlEncoding the byte[], it's one of the overloads hanging off the httpUtility.Encode method. Again, while it was URL encoded, IIS did not like it and served up a "page not found."

After digging around the net I came across a HexEncoding/Decoding class. Applying the Hex Encoding to the encrypted bytes did the trick. The output is url safe. On the other side, I haven't had any problems with decoding and decrypting the hex strings.