Randomly flip bits in the file

bitrot.py

#! /usr/bin/env python
# Randomly flip bits in the file.
import argparse
import random

parser = argparse.ArgumentParser()
parser.add_argument('file', help='the file whose bits to be fliped')
parser.add_argument('count', type=int, default=1, nargs='?', help='number of rounds of bit flipping (default: 1)')

args = parser.parse_args()

with open(args.file, 'rb+') as f:
    f.seek(0, 2)
    n = f.tell()
    for _ in range(args.count):
        k = random.randint(0, n - 1)
        f.seek(k, 0)
        byte = ord(f.read(1))
        f.seek(-1, 1)
        x = 1 << random.randint(0, 7)
        f.write(chr(byte ^ x))