3 ms·

I don't follow your math. If we assume the cost of your password hash matches the cost of a bitcoin hash, I arrive at 2 * 10^6 years, not 4 * 10^39 years. 2^11

• codethief 4y ago
  Yeah, I'm not following that calculation either. Adding to that: > Even assuming just upper/lowercase and 20 characters you are looking at 114 bits of entropy. Upper/lowercase are already 52 characters. If we add digits (0-9) we are already looking at log_2(62^20) = 119 bits of entropy. On that note: Let's assume the password were indeed purely random and had 119 genuine bits of entropy. If you're the attacker and your goal is to do 1000 (≃ 2^10) rounds of SHA1 for each of those 2^119 potential passwords, couldn't you then just try to brute-force the 128-bit key directly, since 119 + 10 >= 128? Put differently, wouldn't the statement "A fully random 20-character alphanumeric password has been brute-forced" amount to saying "AES-128 can be brute-forced"?
• orlp 4y ago
  I... don't know what the hell happened. I was doing the calculation on mobile while on the move and I must've screwed up the parenthesis in the denominator. Embarrassing... Your calculation is correct. My point still stands (2 million years is plenty of time), but my number given was completely off. I can't edit it anymore though.