破解PDF文件，Python 2.7

Question

For an assignment I'm currently doing, I have to crack a locked PDF File. I've got a while loop that creates potential passwords, one of which will crack the PDF File. I also have a program that cracks PDF Files through the use of a wordlist. The code for both programs is as follows:

While Loop:

from random import shuffle
with open('randomwords.txt', 'r') as data:
    data = data.read().split()
    while(True):
        shuffle(data)
        password = ''
        for x in data[:3]:
            password += x
        print password.replace('o', '0')

PDF Cracker:

import PyPDF2
import sys
import optparse

parser = optparse.OptionParser()
parser.add_option('-f', '--file', dest='file', help='encrypted file')
parser.add_option('-w', '--wordlist', dest='word', help='wordlist file')
(options, args) = parser.parse_args()
if options.file == None or options.word == None:
    print('')
    sys.exit()

file = options.file
word = options.word
wordlist = open(word)

pdf = PyPDF2.PdfFileReader(open(file,'rb'))
if not pdf.isEncrypted:
    print('This PDF has no password')
else:
    for line in wordlist.readlines():
        if pdf.decrypt(line.rstrip()):
            print('[+] Password: ' +line)
            sys.exit()
        print('[-] Password not found')

In order to complete this assignment, I have to crack the PDF File, is it possible to combine these two programs, so I can use the loop to crack the file instead of using a wordlist.

This is a bit beyond my current skill level with Python, have been struggling with this problem for a few days now.

Answer 1

1) If you want the program to terminate, we'll have to get rid of the infinite while loop.

We can use the itertools.permutations to get all permutations of selecting 3 words from the wordlist.

For example

wordlist = ['dog', 'cat', 'bat']
for p in itertools.permutations(wordlist, 2):
  print p

will output

('dog', 'cat')
('dog', 'bat')
('cat', 'dog')
('cat', 'bat')
('bat', 'dog')
('bat', 'cat')

So instead of

while(True):
        shuffle(data)
        password = ''
        for x in data[:3]:
            password += x
        password.replace('o', '0')

we iterate over all the permutations

for perm in itertools.permutations(data, 3):
  password = "".join(perm)
  password.replace('o', '0')
  if pdf.decrypt(password):
      print('[+] Password: ' +line)
      sys.exit()
  print('[-] Password not found')

Then instead of attempting to decrypt inside this loop for line in wordlist.readlines(): , you attempt to decrypt inside for perm in itertools.permutations(data, 3):