Xor two strings, assumes you've got a Converters class that converts the bytestring to hex first.

xor_byte_str.rb

class CryptoTools
  def self.xor_str(str_a,str_b)
    if str_a.length != str_b.length
      raise "Length of input strings doesn't match!"
    end
    str_a.bytes.zip(str_b.bytes).map{ |x,y| x^y }.pack("C*")
  end
  def self.hex_xor(hex_a,hex_b)
    Converters.str_to_hex(xor_str(Converters.hex_to_bytes(hex_a),
                                  Converters.hex_to_bytes(hex_b)))
  end
end