#!/usr/bin/python

    import sys

    # ----------------------------------------------------------------------------
    # Crypto4o functions start here
    # ----------------------------------------------------------------------------

    class glfsr:
        def __init__(self, polynom, initial_value):
            self.polynom = polynom | 1
            self.data = initial_value
            tmp = polynom

            self.mask = 1

            while tmp != 0:
                if tmp & self.mask != 0:
                    tmp = tmp ^ self.mask;

                if tmp == 0:
                    break

                self.mask = self.mask << 1

        def next_state(self):
            self.data = self.data << 1

            retval = 0

            if self.data & self.mask != 0:
                retval = 1
                self.data = self.data ^ self.polynom

            return retval

    class sprng:
        def __init__(self, polynom_d, init_value_d, polynom_c, init_value_c):
            self.glfsr_d = glfsr(polynom_d, init_value_d)
            self.glfsr_c = glfsr(polynom_c, init_value_c)

        def next_byte(self):
            byte = 0
            bitpos = 7

            while 1 == 1:
                bit_d = self.glfsr_d.next_state()
                bit_c = self.glfsr_c.next_state()

                if bit_c != 0:
                    bit_r = bit_d
                    byte = byte | (bit_r << bitpos)

                    bitpos = bitpos - 1

                    if bitpos < 0:
                        break

            return byte

    # ----------------------------------------------------------------------------
    # Crypto4o functions end here
    # ----------------------------------------------------------------------------

    def main():
        prng = sprng(int(sys.argv[3], 16), int(sys.argv[4], 16),
            int(sys.argv[5], 16), int(sys.argv[6], 16))

        print "GLFSR D0: using polynom 0x%X, initial value: 0x%X." % (int(sys.argv[3], 16), int(sys.argv[4], 16))
        print "GLFSR C0: using polynom 0x%X, initial value: 0x%X." % (int(sys.argv[5], 16), int(sys.argv[6], 16))

        f = open(sys.argv[1], "rb")
        g = open(sys.argv[2], "wb")

        while 1 == 1:
            input_ch = f.read(1)

            if input_ch == "":
                break

            random_ch = prng.next_byte() & 0xff
            g.write(chr(ord(input_ch) ^ random_ch))

        f.close()
        g.close()

    main()