Count number of possibilities: 20 chars, on each position ca. 70 possibilities, that makes 70**20 = (1.7 * 10**9) * (86400 * 4) * 70**12 Let's say you check 1.7 * 10**9 operations per second, that means 4 * 70**12 days to check all possibilities. How long does your script work already? :)