Skytale cipher

A slightly less simple obfuscation for a slightly less simple substitution cipher. The next stop in my tour of old forgotten encryption ciphers is this skytale implementation. This either takes a file as a parameter to encrypt in skytale, or provided no input encrypt's it's __DATA__.

#!/usr/bin/perl

open DATA,$ARGV[0]if$ARGV[0];$;=$0=~y~a-z~~;map{m'(\d+)(?{$*=chr$,+65;
+push@{$*},
$^N;$.{$*}++;$,=$,<$;?++$,:0})'}grep!/^10$/,map ord,split//,join'',<DA
+TA>; print
join '' , map chr , @ $_ for 'A' .. ( sort keys ( % . ) ) [ -1 ] ;  pr
+int "\n" ;

__DATA__
In cryptography, a scytale (also known as skytale) is a tool used to p
+erform a
transposition cipher, consisting of a cylinder w/ a strip of paper wou
+nd around
it on which is written a message across the windings, with the ciphert
+ext
consisting of the unwound paper.  This is one way to implement such a 
+cipher.
[download]

--chargrill

$,=42;for(34,0,-3,9,-11,11,-17,7,-5){$*.=pack'c'=>$,+=$_}for(reverse s
+plit//=>$*
){$%++?$ %%2?push@C,$_,$":push@c,$_,$":(push@C,$_,$")&&push@c,$"}$C[$#
+C]=$/;($#C
>$#c)?($ c=\@C)&&($ C=\@c):($ c=\@c)&&($C=\@C);$%=$|;for(@$c){print$_^
+$$C[$%++]}
[download]

Comment on Skytale cipher Select or Download Code

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Re: Skytale cipher
by turo (Friar) on May 04, 2006 at 04:02 UTC

Good Implementation :-) ...

Your scitale has a width (W) denoted by the number of lower cups characters the filename has, plus one.

Then, you use W arrays for storing each character from the plaintext; first character on the plaintext to the array[0], the second to the array1, and so on up to reach the arrayW-1, the next char to the first array[0], etc.

Cool!, i've made an implementation of this cipher (i like too much these topic) a long time ago (i do not remember where did i put it), but for sure my impl. was unobfuscated an i think i made W reads of the plaintext for encoding and decoding. Not too optimal, but easy to understand :-) (ummm... i don't rememeber if i've made it in perl ... or it was in awk? ... anyway)

perl -Te 'print map { chr((ord)-((10,20,2,7)[$i++])) } split //,"turo"'

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