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$_=q|P"\e[2J\n";SQw{my$s;select$s,$s,$s,H}SQc{P"\e[12;1f\n"}($_=pop)?o
+pen+DAT
A,$_:$@;$k=N"",MQuc,grep/[a-z]/,M$.{$_}++or$_,$0=~/\w/g;@s=($k=~/./g,g
+rep/[^J
...
Vigenere cipher systems then in use. The Playfair is thus significantl
+y harder
to break since the frequency analysis used for simple substitution cip
+hers
does not work with it.

$,=42;for(34,0,-3,9,-11,11,-17,7,-5){$*.=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[$%++]}