09-01-2022, 04:39 PM
The Polybius square (with a slight modification) was what I meant in You are not allowed to view links. Register or Login to view..
If you use one sub-alphabet for rows, another one for columns, then you obtain intra-bigram positional rigidity not unlike one the VMS exhibits. What results is in its essence a verbose cipher, so the conditional character entropy drops - even more than with the trivial verbose cipher which I provided as an example in my recent blog post, but less than for the VMS. The procedure of course doubles the average word length, but then one is free to introduce fake spaces to bring it back down, and what's valuable is that fake spaces can be introduced arbitrarily on sub-alphabet 1 to sub-alphabet 2 transition, since "real" spaces would always be on the opposite transition, which makes the two easily detectable.
I will make a blog post about that when I have more time. There are further simple developments of the Polybius square concept, I still have to check what opportunities they bring in terms of "bringing it closer to Voynichese".
The concept of the Polybius square is very simple and very easily re-invented. I can imagine it being independently re-invented by the VMS creator, especially given such famous example of matrix placement of a sequence of characters as the Sator square.
If you use one sub-alphabet for rows, another one for columns, then you obtain intra-bigram positional rigidity not unlike one the VMS exhibits. What results is in its essence a verbose cipher, so the conditional character entropy drops - even more than with the trivial verbose cipher which I provided as an example in my recent blog post, but less than for the VMS. The procedure of course doubles the average word length, but then one is free to introduce fake spaces to bring it back down, and what's valuable is that fake spaces can be introduced arbitrarily on sub-alphabet 1 to sub-alphabet 2 transition, since "real" spaces would always be on the opposite transition, which makes the two easily detectable.
I will make a blog post about that when I have more time. There are further simple developments of the Polybius square concept, I still have to check what opportunities they bring in terms of "bringing it closer to Voynichese".
The concept of the Polybius square is very simple and very easily re-invented. I can imagine it being independently re-invented by the VMS creator, especially given such famous example of matrix placement of a sequence of characters as the Sator square.