I know I have to be very vague, and I share your pain, so I’ll see if I can help you interpret the clue. The clue is a FordKey which is very similar to the name of the cipher used.
[Edited by Harry]
See if that helps, but really you should try researching into the different variations of the cipher used in the previous Janus Files
[Moderators feel free to censor stuff if I have given away too much]