A little while back, I asked Augusto Buonafalce about Renaissance cryptographer Giovan Battista Bellaso’s challenge ciphers, completely unaware that he seems to have published more articles on them than anyone else on the planet. (Shame on me for not subscribing to Cryptologia, I really ought to.)
In fact, Bellaso published two sets of challenge ciphers in his cryptography manuals: a set of three long ones in 1553 (which I don’t have copies of), and a set of seven short ones in 1564 (which I do). For me, the mystery is why nobody has cracked any of these in 450 years… compared to the Voynich Manuscript’s multilayered (and horrendously tangled) cryptography, they can’t be that hard, surely?
Here’s a link to the short page I’ve just put up on Bellaso’s challenge ciphers. Don’t forget that the “=” signs at the line-ends are almost certainly hyphens, and not part of the cipher. Good luck! 😉