# File lib/rack/protection/base.rb, line 115
      def secure_compare(a, b)
        return false unless bytesize(a) == bytesize(b)

        l = a.unpack("C*")

        r, i = 0, -1
        b.each_byte { |v| r |= v ^ l[i+=1] }
        r == 0
      end