#!/usr/bin/perl -w

use strict;
use warnings;

my %p2C;
my %C2p;

sub key {
    my $kp= shift;
    my $caesar= shift;
    my $a=0;
    my $k;
    $p2C{' '}=' ';
    $C2p{' '}=' ';
    foreach (split(//, $kp)) {
        if (not exists $p2C{$_}) {
            #print $_;
            $k=chr(ord('A')+(($a++)+$caesar)%26);
            $p2C{$_}=$k;
            $C2p{$k}=$_;
        }
    }
   foreach ('a'..'z') {
        if (not exists $p2C{$_}) {
            $k=chr(ord('A')+(($a++)+$caesar)%26);
            $p2C{$_}=$k;
            $C2p{$k}=$_;
        }
    }
            
}  
sub printKeys {
    my $href = shift;
    print "\nCT: ";
    print(($_).' ') foreach (sort keys %{$href});
    print "\npt: ";
    print(($$href{$_}).' ') foreach (sort keys %{$href});
    print "\n";
}

key ('thequickbrownfoxjumpsoverthelazydogs',10);

printKeys(\%p2C);
printKeys(\%C2p);
print "----------------------------------------------------------\n";
undef %p2C;
undef %C2p;
key ('thequickbrown',10);
printKeys(\%p2C);
printKeys(\%C2p);

##</code><code>##

C:\chas_sandbox>keyonly.pl

CT:   a b c d e f g h i j k l m n o p q r s t u v w x y z
pt:   F S Q I M X J L P Z R E A W U B N T C K O D V Y H G

CT:   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
pt:   m p s v l a z y d g t h e q u i c k b r o w n f x j
----------------------------------------------------------

CT:   a b c d e f g h i j k l m n o p q r s t u v w x y z
pt:   X S Q Y M Z A L P B R C D W U E N T F K O G V H I J

CT:   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
pt:   g j l m p s v x y z t h e q u i c k b r o w n a d f

C:\chas_sandbox>