StudSec CTF Token Challenge Cracker

cracker.py

import logging # Have to use logging to print inside signals
import time
import fcntl
import os
import signal
from randcrack import RandCrack
import sys

dirname = "/tmp/"
filename = "py-log1376543.txt"

rc = RandCrack()
is_ready = False
queue = []

def handler():
    last_line = read_file()[-1]
    logging.info(f"New passwd change: {last_line}")
    if is_ready:
      logging.info(f'Next code prediction: {"".join(rc.predict_choice("0123456789abcdef") for _ in range(10)).upper()}')
    else:
      queue.append(last_line)

def main():
  global is_ready

  start_file_listener(filename, handler)
  
  lines = read_file()
  randints = lines[1:701]
  codes = lines[704:]

  start_timer("Seeding with 624 initial ints...")
  for _ in range(624):
    rc.submit(int(randints.pop(0)));

  start_timer(f"Feeding the last {len(randints)} ints...")
  while len(randints) > 0:
    real = int(randints.pop(0))
    pred = rc.predict_randint(0, 4294967294)
    if not real == pred:
      sys.exit(f"Something went wrong while feeding ints. Real = {real}, Pred = {pred}")

  total_len = len(codes)
  logging.info(f"Feeding all the {total_len} previous codes.")
  start_timer(f"This will take a while, go grab some coffee...  (Approx {2500 * total_len / 1e+6} sec)")
  while len(codes) > 0:
    prg = (total_len - len(codes)) / total_len * 100
    if (prg > 0 and prg % 5 == 0):
      logging.info(str(round(prg)) + '%...')
    for _ in range(10):
      #rc.predict_choice('0123456789abcdef')
      rc.predict_randbelow(16)

    codes.pop(0)

  handle_queue()
  reset_timer()

  logging.info(f'Next code prediction: {"".join(rc.predict_choice("0123456789abcdef") for _ in range(10)).upper()}')
  is_ready = True

def handle_queue():
  while len(queue) > 0:
    for _ in range(10):
      rc.predict_choice('0123456789abcdef')
    queue.pop(0)
  
  if len(queue) > 0:
    handle_queue()


#for pos in range(0, 700):
#    starting = randints[int(pos)]
#    rc = RandCrack()
#    for pos2 in range(int(pos), min(int(pos)+624, 700)):
#        rc.submit(int(randints[pos2]));
#    if rc.predict_randint(0, 4294967294) == randints[min(int(pos)+625, 699)]:
#        print("Pog?")
#    else:
#        print("F")
def read_file():
    with open(dirname + filename, "r") as f:
      return f.readlines()

prevLastModifiedTime = 0
def start_file_listener(filename, handler): 
    def check_changes(*_):
      global prevLastModifiedTime
      lastModifiedTime = os.stat(filename).st_mtime
      if lastModifiedTime != prevLastModifiedTime:
        prevLastModifiedTime = lastModifiedTime
        handler()
    signal.signal(signal.SIGIO, check_changes)
    fd = os.open(dirname, os.O_RDONLY)
    fcntl.fcntl(fd, fcntl.F_SETSIG, 0)
    fcntl.fcntl(fd, fcntl.F_NOTIFY, fcntl.DN_MODIFY | fcntl.DN_CREATE | fcntl.DN_MULTISHOT)

start_time = 0
def start_timer(line):
  global start_time
  if (start_time > 0):
    reset_timer()

  start_time = time.time()
  if line:
    logging.info(line)

def reset_timer():
  global start_time
  logging.info("Took {}ms.".format(round((time.time() - start_time) * 1000)))
  start_time = 0

logging.basicConfig(level=logging.NOTSET, format='%(message)s')
main()
while True:
    time.sleep(10000)