xor_byte_strings

# File actionpack/lib/action_controller/metal/request_forgery_protection.rb, line 386
      def xor_byte_strings(s1, s2) # :doc:
        s2_bytes = s2.bytes
        s1.each_byte.with_index { |c1, i| s2_bytes[i] ^= c1 }
        s2_bytes.pack("C*")
      end