Re: Double transposition cryptanalysis
From: Stewart Strait (sstrait1_at_san.rr.com)
Date: Mon, 15 Aug 2005 08:42:03 GMT
Rob Sullivan <firstname.lastname@example.org> wrote:
> I've written a program to break double transposition ciphers based on
> FairPlay, a Playfair cipher cracker. The original program used shotgun
> hill-climbing, so all I really had to do was modify the
> Playfair-specific parts.
> The source code is below - I'd be interested in any comments or
1. How well has your code worked so far?
2. It would save time if you could give a URL for the file
trigrams_npf.txt used by your code.
3. If anyone wants double incomplete columnar transposition
test/challenge examples, perhaps you might be interested in:
There are 10 examples in the 08 file and 20 in the 09 file.
The plaintext should be fairly normal English, but text may
begin and/or end in the middle of a word. The two transpositions
in a given example have the same key. The plaintext length is
always 907 letters, which is likely to make these examples easier
than is typical for this system.
stos08: 13<=key length<=22 [10 examples]
stos09: 10<=key length<=15 [20 examples]
Plaintext is not original.--