gistfile1.txt

  KEY = ['4E', '65', '78', '6F', '6E', '49', '6E', '63', '2E']
  def self.decrypt(packet, increment)
    0.upto(packet.length-1) do |i|
      packet[i] = (packet[i] ^ (KEY[i % 9].hex))
      packet[i] = (packet[i] ^ (i/9) )
      packet[i] = (packet[i] ^ increment)   
    end
    
    #todo optimize conversion
    return packet.map {|x| x.to_s(16).hex.chr}.join