Thanks for the criticism! I've not played many cryptograms, so I wasn't familiar with that idea. I wouldn't have called it a "complete shuffle" though. An "incomplete shuffle", maybe :)
I've added a bit to my shuffling function to ensure a derangement. It's a bit quick and dirty...
sub gen_random_key{
####sub fisher_yates_shuffle {
my @array = split ("", $alpha);
my @alpha = @array;
for (my $i = @array; --$i; ) {
my $j = int rand ($i+1);
next if $i == $j;
@array[$i, $j] = @array[$j, $i];
}
for (0..$#alpha){
$decrypt{$alpha[$_]} = $array[$_];
$encrypt{$array[$_]} = $alpha[$_];
}
#ensure a derangement
for (0..$#alpha){
if ($alpha[$_] eq $array[$_]) {
gen_random_key();
#warn 'key not deranged, setting another..';
return;
}
}
}