Make password/hash verification algorithm more efficient

Question

I am trying to guess the paswords from the etc/shadow file(it has 43 user/passwords). And I have been given some hints about the passwords:

Length is between 4 and 8 characters
There can be only 2 numbers and only at the end
Capital letters only in the beginning

So I started just with a small group composed by 4 character with 2 digits in it. But it takes so much time to process:

import crypt
import string
import itertools
import datetime

dir = "shadow3"
file = open(dir, 'r').readlines() #Read all the 43 hashes

username = []
hashed = []
c = 0
cc = 0

for x in file: #Split the hash and the username
    usr, hshd, wtf, iss, this, thing, here, doing, example = x.split(':')
    username.append(usr)
    hashed.append(hshd)
#GRUPO1 4 caracteres 2 numeros
letters = string.ascii_lowercase
digits = string.digits
grupo1=[]
group1=itertools.product(letters,repeat=2)
group1b=itertools.product(digits,repeat=2)
for x in itertools.product(group1,group1b):  #Join the possible iterations
  string=''.join([''.join(k) for k in x])
  grupo1.append(string)
print(len(grupo1))
for y in grupo1:#Get the one of the iterations and try it 
  prueba=y
  for x in hashed: #Verify if that iteration is the password to any of the 43 users
    rehashed = crypt.crypt(prueba, x)
    if rehashed == x: #Password is found
        print('La contraseña del usuario ' + username[c] + ' es ' + prueba)
        cc = 1
    c = c + 1
if cc == 0: #after all iterations password is not found
    print('Lo sentimos "' + prueba + '" no es la contraseña de ningun usuario')

How can I improve the efficiency of this? I have a GTX 1070 if it helps for any kind of GPU processing.

If your code works without errors, Code Review might be a better place to ask on. Stack Overflow soecializes in not-working code. — Jongware
– Jongware, Commented Nov 23, 2018 at 16:24

yoonghm · Accepted Answer · 2018-11-23 16:36:04Z

1

I believe your code has errors. Your problem could be re-modelled so that it could be faster:

Generate all combination of possible passwords, based on your criteria - Length is between 4 and 8 characters - There can be only 2 numbers and only at the end - Capital letters only in the beginning

Generate crypt() on each of the combinations Compare passwords vs the crypted values.

answered Nov 23, 2018 at 16:36

yoonghm

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musbur · Accepted Answer · 2018-11-23 15:02:41Z

0

Luckily, Python comes with a profiler to help solve this kind of problem. Look at the cProfile documentation.

answered Nov 23, 2018 at 15:02

musbur

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