How easy is it to create a cipher which is very hard to break?

[Mark Knowles]

Mark, if you could produce text with Voynichese properties (without copying or looking at Voynichese itself while you are doing it), then it means you have a strong understanding of its structure and would potentially be able to describe it.

That, in itself, would be an achievement because being able to describe it can help to differentiate between linguistic, conlang, or other patterns.

Why can't I copy portions, if I wish, and why can't I look at Voynichese itself while I am doing it?

Obviously if I make a perfect copy that is of little interest, but it should be perfectly OK for me to copy bits and paste them together if and when I wish.

Again it seems unnecessary to prevent someone from looking at Voynichese as and when they produce their Voynichese like text.

These restrictions would certainly make things harder, but it seems to me to be completely unnecessary. The author of the Voynich could copy portions if he/she wished. The author of the Voynich could look at the rest of what he/she had already written. Why impose restrictions that did not apply to the author?

It is a mistake to think that being able to produce Voynichese text necessarily would mean that you have a strong understanding of its structure and would be able to describe it. I can walk, but I can't describe very precisely what I am doing. There are lots of things that we can do that we can't describe as to what we are doing. So whilst making up text manually requires some conscious consideration, it doesn't necessarily make the process very easy to turn into an algorithm.

I think you may be getting ahead of yourself with what you interpret as to what one could necessarily conclude from being able to reproduce Voynichese text.

I think it is important to distinguish between manually produced text and automatically produced text such as Rugg and others have done.