timing_attack.py

"""
Extremely crude example of a timing attack
"""

import time
import timeit

actualPassword = '0BEA0239'

def checkpassword(passwd):
    for a, b in zip(passwd, actualPassword):
        if a != b:
            return False

    if len(actualPassword) != len(passwd):
        return False
        
    return True

possibleDigits = 'ABCDEF0123456789'
password = ''

while True:
    timings = {}
    digits = []
    for i in possibleDigits:
        newpassword = password + i
        t = timeit.Timer(lambda: checkpassword(newpassword))
        digits.append((t.timeit(number=30000), str(i)))

    probable_digit = sorted(digits)[-1][1]
    password += str(probable_digit)
    print("Found digit %s, trying password %s" % (probable_digit, password))
    if checkpassword(password):
        print("Cracked the password!")
        break
    else:
        print("Not found it yet, carrying on")