Ok I found the site (linked from the Wikipedia Page) but I can't do it by paper, or on the Rumkin site. We obviously got the correct message, but I am somewhat curious about how the SectretCodeBreaker site ran it's algorithm.
Anyway I might look at the text later today.
A theory:
- The gamemaster used that particular site to encrypt the message.
- That site has an algorithm which is not 100% "correct", if by correct you mean completely in line with the classic description of the (Vignere) Autokey cipher.
- Hence, the only realistic way to decode the message would be to reverse it through that specific site's algorithm, which is why we had no luck with any of the other tools.