#!/usr/bin/perl -w

%chars = (

    'a' =>  1,
    'b' =>  2,
    'c' =>  3,
    'd' =>  4,
    'e' =>  5,
    'f' =>  6,
    'g' =>  7,
    'h' =>  8,
    'i' =>  9,
    'j' =>  10,
    'k' =>  11,
    'l' =>  12,
    'm' =>  13,
    'n' =>  14,
    'o' =>  15,
    'p' =>  16,
    'q' =>  17,
    'r' =>  18,
    's' =>  19,
    't' =>  20,
    'u' =>  21,
    'v' =>  22,
    'w' =>  23,
    'x' =>  24,
    'y' =>  25,
    'z' =>  26,
);
%numbers = (

    1 => 'a',
    2 => 'b',
    3 => 'c',
    4 => 'd',
    5 => 'e',
    6 => 'f',
    7 => 'g',
    8 => 'h',
    9 => 'i',
    10 => 'j',
    11 => 'k',
    12 => 'l',
    13 => 'm',
    14 => 'n',
    15 => 'o',
    16 => 'p',
    17 => 'q',
    18 => 'r',
    19 => 's',
    20 => 't',
    21 => 'u',
    22 => 'v',
    23 => 'w',
    24 => 'x',
    25 => 'y',
    26 => 'z',
);


$total_characters = keys %chars;

print "total: $total_characters\n";

print "Enter a string to encrypt: ";

$clearstring = <STDIN>; chomp($clearstring); 

print "Now enter a key to encrypt it with: ";
$key = <STDIN>;
chomp($key);

$string_size = length($clearstring);
$key_size = length($key);

$i = 0;
$ik = 0;
@string_array = split(//, $clearstring);
@key_array = split(//, $key);

$encrypted_string = "";

while ($i < $string_size) {

    $sum = $chars{$string_array[$i]} + $chars{$key_array[$ik]};
    $mod_sum = $sum % $total_characters;

    $encrypted_string .= $numbers{$mod_sum};

    if ($ik == ($key_size - 1)) {
        $ik = 0;
    } else {
        $ik++;
    }

    $i++;
}


print "\nEncrypted String: $encrypted_string\n";