Engineering your own voynich

[oshfdk]

If spaces are encoded, they should account for 12-17% of all characters (I sampled a few English texts.) In this post I assume there are spaces and they are encoded as dedicated ciphertext codes; either of the assumptions may be not true for the actual cipher.

The following are the top prefixes and suffixes of all words (the percentage is computed using the number of word tokens with the prefix/suffix):

Top most common prefixes:
T: 22.65%
F: 20.09%
K: 16.67%
Ti: 15.38%
m: 12.39%
Ka: 9.83%
f: 9.83%
n: 8.97%
Fi: 6.41%

Top most common suffixes:
n: 28.63%
g: 13.25%
un: 13.25%
yun: 13.25%
uy: 8.55%
y: 8.55%
an: 7.69%

There are several potential prefixes that could encode the space character, but only two suffixes fall in the right frequency bracket: -g and -yun.

If we look at distributions of -g and -yun in the text, it looks like there is a large gap of 38 words without -g suffix and only of 25 words for -yun suffix, which makes interpreting -yun as the space slightly more likely.

If -yun is a space, then the following excerpt seems to indicate that Fiii and Fai are very short words (not unlike "it is" in the other cipher). Another short word then would be Tai, near the beginning of the ciphertext, not in the image below.