obfuscates a file using 1-byte xor

filexor.py

#!/usr/bin/env python

from struct import unpack, pack
import sys

x = ''
with open(sys.argv[1], 'rb') as f:
    x = f.read()

with open(sys.argv[2], 'wb') as f:
    for i in xrange(0,len(x)):
        y = unpack('b', x[i])[0]
        y ^= 0x55
        f.write(pack('b', y))