A co-worker of mine made a tool to help generate the keys. It only works on CryptoBit v1 though. The key is made up 2 parts, one to identify if the file is infected and the other half to decrypt the file. He uses some brute force method using the magic numbers from the file signature to generate part of the key. It usually takes between 3-8 hours to run. With just a couple of the infected files like a jpg, doc, and pdf, it will usually work. Having the same unaffected file also helps speed up the process since some file types have several different headers and trying to match them takes time.
Here is the file signature page I use to match the file type: http://www.garykessler.net/library/file_sigs.html
If you want me to give a try, you can send me a couple files....Like I said, only CryptoBit v1