PHP: Shorter/obscured encoding for a URL embedded in another URL?

[al-shami]

I'm writing myself a script which basically lets me send a URL and two integer dimensions in the querystring of a single get request. I'm using base64 to encode it, but its pretty damn long and I'm concerned the URL may get too big.Does anyone know an alternative, shorter method of doing this? It needs to be decode-able when received in a get request, so md5/sha1 are not possible.Thanks for your time.Edit: Sorry - I should have explained better: Ok, on our site we display screenshots of websites that get posted up for review. We have our own thumbnail/screenshot server. I'm basically going to be having the image tag contain an encoded string that stores the URL to take a screenshot of, and the width/height of the image to show. I dont however want it in 'raw-text' for the world to see. Obviously base64 can be decided by anyone, but we dont want your average joe picking up the URL path. Really I need to fetch: url, width, height in a single GET request.