Vigenere Encryption

Vigenere.rb

#!/usr/bin/ruby

class String; def ord; self[0]; end; end

phrase = "tobeornottobethatisthequestion"
keyword = "hamlet"
len = keyword.length

keyindex = 0

phrase.each_char do |c|
        print ((c.ord - 97 + keyword[keyindex].ord - 97) % 26 + 97).chr
        keyindex = (keyindex + 1) % len
end