Lori_encrypt.rb

phrase = "This is my secret message."

  alpha_values =
    {
      "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, " "=> " ", "."=> ".",
      ","=>","
    }

    code = 13
    positions = phrase.upcase.split('').map {|position| alpha_values[position] || position}
    encrypted_phrase = positions.map do |value|
      if value.is_a?(Fixnum)
        new_value = (value + code) % 26 # change these back into letters
        if new_value == 0
          new_value = 26
        end
        alpha_values.invert[new_value]
      else
        value
      end
    end

    encrypted_phrase.join.capitalize