a = 'Wkh_Txlfn_Eurzq_Ira_Mxpsv_Ryhu_Wkh_Odcb_Grj'
   import string
   def rotn(n):
       from string import ascii_lowercase as lc, ascii_uppercase as uc
       mapping = string.maketrans(lc + uc, lc[n:] + lc[:n] + uc[n:] + uc[:n])
       return mapping
   for n in xrange(26):
      a.translate(rotn(n))

use 5.010;
use warnings;

my $original = lc "Ceterum censeo Carthaginem esse delendam";

my $cyphered = $original;
$cyphered =~ tr/a-z/k-za-j/;
say $cyphered;

my $decyphered = $cyphered;
$decyphered =~ tr/k-za-j/a-z/;
say $decyphered;

class Caesar
  def initialize(shift, alphabet = ('a'..'z').to_a.join)
    i = shift % alphabet.size #I like this
    @decrypt = alphabet
    @encrypt = alphabet[i..-1] + alphabet[0...i]
  end

  def encrypt(string)
    string.tr(@decrypt, @encrypt)
  end

  def decrypt(string)
    string.tr(@encrypt, @decrypt)
  end
end

 private final String ALPHABET = "abcdefghijklmnopqrstuvwxyz";
 public String encrypt(String plainText,int shiftKey)
 {
       plainText = plainText.toLowerCase();
       String cipherText="";
       for(int i=0;i<plainText.length();i++)
       {
            int charPosition = ALPHABET.indexOf(plainText.charAt(i));
            int keyVal = (shiftKey+charPosition)%26;
            char replaceVal = this.ALPHABET.charAt(keyVal);
            cipherText += replaceVal;
       }
       return cipherText;
 }
 public String decrypt(String cipherText, int shiftKey)
 {
       cipherText = cipherText.toLowerCase();
       String plainText="";
}