Eggswap Cypher

import os

def hexGenerate(_bytes):

    if type(_bytes) == str:

        for i in range(len(_bytes)//8):
            hexString = ''.join([hex(ord(char)) for char in _bytes[0+i*8: 8+i*8]])

            yield hexString

    elif type(_bytes) == file:

        for i in range(os.path.getsize(_bytes.name)//8):
            hexString = ''.join([hex(ord(char)) for char in _bytes.read(8)])

            yield hexString

def eggswap(data, key):

    if len(key)%8 != 0: return False, 'Key lenght not equal to 8'

    hex_gen = hexGenerate(data)

    key = ''.join([hex(ord(char)) for char in key])
    key1, key2 = key.split('0x')[1:5], key.split('0x')[5:9]

    for b in key1:
        if len(b) == 1: key1[key1.index(b)] = '0'+b

    for b in key2:
        if len(b) == 1: key2[key2.index(b)] = '0'+b

    result = ''

    for byte in hex_gen:
        byte1, byte2 = byte.split('0x')[1:5], byte.split('0x')[5:9]

        for b in byte1:
            if len(b) == 1: byte1[byte1.index(b)] = '0'+b

        for b in byte2:
            if len(b) == 1: byte2[byte2.index(b)] = '0'+b

        for byte, key in [(byte1, key1), (byte2, key2)]:

            for i in range(4):

                hex1, hex2 = eval('0x'+byte[i][0]), eval('0x'+byte[i][1])
                hex3, hex4 = eval('0x'+key[i][0]), eval('0x'+key[i][1])

                hex5 = 2*hex4-hex1
                if hex5 > 15: hex5 -= 16
                if hex5 < 0: hex5 += 16
                hex5 = hex(hex5)

                hex6 = 2*hex3-hex2
                if hex6 > 15: hex6 -= 16
                if hex6 < 0: hex6 += 16
                hex6 = hex(hex6).replace('0x','')

                result += hex5+hex6

    return ''.join(chr(eval('0x'+i)) for i in result.split('0x')[1:])

text = open(r'C:\Users\Gabriel\Documents\GADI2\Test\Test.gp')
key = '_)734hZ/'

cipher_text = eggswap(text, key)
open(r'C:\Users\Gabriel\Documents\GADI2\Test\Test.txt', 'w').write(eggswap(cipher_text, key))