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Re: VMs: Cardan grille


Zitat von Jacques Guy <jguy@xxxxxxxxxxxxxxxx>:

> ...
> It can be handled by standard cryptological methods if the same grilles 
> have been used and reused enough times each. In particular, the pages
> written with the same grille will all show "squares" containing a
> single character _always_ at the same coordinates. But, since the
> manuscript was written by hand, the characters of the filler text
> will appear in slightly different places from page to page (not
> a very clear explanation, I'm afraid. Try encrypting "hello world"
> with a small 7x7 grill with 10 holes in it, filling the spaces
> in between with text written by hand. Then try again on another
> sheet of paper, with a different 10-letter plaintext. And again.
> Now compare the three. The plaintext letters are the only ones
> to be positioned exactly the same relatively to one another)

Sorry, I don't get it. Of course, if you enciphered "hello world" time after 
time, you would get the described effect, but it don't see it happening if I 
encipher a different plain text on every page. (Which would probably be the 
standard use case.

Or were you saying that letters in the grille openings will over time exhibit a 
statistically significant behaviour? (Ie while the slots covered with the grill 
will see a random letter distribution, the grille openings will show a distinct 
letter frequency distribution?)

Even in that case I'd assume you'd have to have a _large_ piece of text before 
you can go to work.

Or did I fail to understand the idea...?



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