Positional Mimic Cipher (PM-Cipher)

[oshfdk]

The results I ppsted to René comment about entropy are the results of decoding the full De docta ignorantia text.

Yes, I have the code. Need to clean it a bit, and publish. I would like to publish a paper about this together wirh the code, but firstly I wanted some feedback from the ninja comunity if it is really interesting or not.

As far as I understand, the lowering of entropy happens because of three factors: 1) some of the uncertainty is off-loaded to residuals; 2) some characters are encoded via ciphertext bigrams, so the cipher is a bit verbose; 3) for short texts some of the entropy is captured by the structure of the table.

While 1 and 2 are easy to explain and would work for text of any size, 3 should not really scale with the size of the text.

This one looks interesting to me personally, because in principle it's realistic for a book. Residuals can be encoded via some character traits (like curvy/pointy l's, etc) and overall you don't even need a table this huge, something like 8-9 columns should be more than enough. To make it mimic more of the properties of Voynichese it should probably be a one-to-many cipher, but maybe instead of resetting the table at each word break the encoding can just keep rolling, only resetting when reaching a terminal character in the table (say, y / n).

Overall, I suspect this cipher primarily keeps the entropy low by expanding the effective character set via residuals. Nothing wrong with that, but essentially this is the same old idea that the actual alphabet of Voynichese is not ~15 common characters, but ~30-40 common characters with two or more distinct l's, two or more distinct r's, etc.