#!/usr/bin/perl
use strict;

# name:     shift-cipher
# author:   ap0calypse ( ap0calypse@agitatio.org )
# version:  0.1 ( 2008-02-08 )
# license:  DO WHATEVER YOU WANT!
# purpose:  reads a sentence from STDIN an returns all 
#           possible ciphered sentences. currently, all
#           input will be converted to lowercase letters. maybe
#           future versions will include support for uppercase
#           letters too.

chomp (my $input = <>); # all input lowercase / without newline
$input = lc $input;


# the function that does the dirty work

sub cipher_sentence {
    
    my ($hi_limit, $lo_limit) = (122, 96);          # z, a-1 for calculating
    my ($sentence, $cipher_value) = (shift, shift);
    my @letters = split //, $sentence;
    my @sentence_ciphered;

    for my $letter (@letters) {
        my $num_letter = ord $letter;
        if ($num_letter != 32) {
            $num_letter += $cipher_value;
            if ($num_letter > $hi_limit) {
                my $shiftval = $num_letter - $hi_limit;
                $num_letter = $lo_limit + $shiftval;
            }
            push @sentence_ciphered, chr $num_letter;
        }
        else {
            push @sentence_ciphered, " ";
        }
    }
    push @sentence_ciphered, "\n";
    return @sentence_ciphered;
}

# returning all possibilities
for (1 .. 25) {
    print "shift by: $_ :\t", &cipher_sentence($input, $_);
}