Remember md5? - 40 points

Writeup by poortho

Problem Statement: Remember md5?

Oh. Those good old days of md5 and huge rainbow tables. I get nostalgic just thinking about it. Well, you can’t use one of those to break my password. It still isn’t very secure though. I only used my favorite characters ‘a’, ‘b’, and ‘c’. I remember it being about 14 characters long. The hash is 1b657b7fe26eda5b3c1309d340f1674d.

Hint:

When all else fails, try brute force.

Writeup

To solve this problem, we can simply brute force all possible combinations of the characters a, b, and c.

Note that the problem said 'about 14 characters' - this means that it may not be exactly 14. Here's my code:

import itertools
import md5

for x in range(20):
    keywords = [''.join(i) for i in itertools.product(['a','b','c'], repeat = x)]
    for y in keywords:
        if md5.new(y).hexdigest() == "1b657b7fe26eda5b3c1309d340f1674d":
            print y

Run it, and we get the flag!

Flag

abbabcbabcbabcb