Polyphonic Cipher?

[Dobri]

What if the cipher manuscript is encoded with some kind of a polyphonic cipher, a precursor to ciphers of this kind which were developed starting from the second half of the 15th century?

For starters, let me list some clues pointing in this direction:

- excessive use of the symbol o;

- seemingly "predictable" content;

- low entropy; 

etc.

Perhaps the benched diacritical marks could be used to switch from one encoding mode to another?

[oshfdk]

Perhaps the benched diacritical marks could be used to switch from one encoding mode to another?

Just to make sure I understand this, polyphonic means several possible plaintext characters to one ciphertext character, right? You are not allowed to view links. Register or Login to view.

And switching between encoding modes would be called polyalphabetic?

[Dobri]

For a simplified version, one could think of only one alphabet (polyphonic but not truly polyalphabetic) and how to  switch between symbols of said alphabet. For example, the symbol o could be used to represent several other symbols at distinct positions triggered by benched diacritical marks, gallows or something else entirely. Like that the frequency analysis would show an excess of o symbols.

[Dobri]

In addition, imagine not just several distinct plaintext characters to one ciphertext character but also several plaintext vords or symbol combinations to one ciphertext vord or symbol combination. This could explain the observed reduplication to a certain extent.
Also, there seems to be a peculiar divisibility by 10 for some vords or symbol combinations which is difficult to trace statistically because a number of folios are missing.

[oshfdk]

One potential problem is that classical polyalphabetic polyphonic ciphers would lead to quite a few repeated characters in the ciphertext, as seen in the examples in the article I linked. In Voynichese, with the exception of I/E clusters, repeated characters are quite rare.

But I'm not  sure we are talking about the same thing. Could you give a short example of the type of encoding that you have in mind?

[nablator]

What if the cipher manuscript is encoded with some kind of a polyphonic cipher, a precursor to ciphers of this kind which were developed starting from the second half of the 15th century?

Actually the most common medieval cipher (next consonant-for-vowel replacement) is polyphonic. You are not allowed to view links. Register or Login to view.

Perhaps the benched diacritical marks could be used to switch from one encoding mode to another?

So you actually mean a "stateful" cipher or code, not a polyphonic one.