5 ms·

In the context of web authentication, does entropy even matter (beyond an extremely low threshold)? Are there any attacks that actually occur that are defeated

In the context of web authentication, does entropy even matter (beyond an extremely low threshold)? Are there any attacks that actually occur that are defeated by increasing entropy? AFAIK basically all the auth attacks we see today are from password re-use, and out-of-band authentication, neither of which password entropy has an effect on. "Summer2024!" is perfectly fine, if you use it for exactly one service. Frankly, "1235" is probably fine. No one is out there brute-forcing passwords.

mr_mitm 2y ago
> "Summer2024!" is perfectly fine, if you use it for exactly one service. Frankly, "1235" is probably fine. No one is out there brute-forcing passwords. Respectfully, I disagree. "Summer2024!" is probably the second password I'd try after the username itself if I have to guess a password. Use it in a password spraying attack on a company with 500 users and you will get a few hits, I promise.
- coldpie 2y ago
  It's a fair point, but I think my argument still stands. Guessability is a different property from entropy, yeah? "Summer1975!" has the same entropy, but you probably wouldn't have put that into your password sprayer.
  - joshka 2y ago
    Summer1975! would be equally likely to be checked by a password sprayer. It has the same number of hits on HIBP, and falls into a category where heuristic password guess algorithms would generally group them as being the same thing.
- nemo8551 2y ago
  My old work used to give a default month-year-org name and an exclamation mark. The majority of people who still used it was insane. LinkedIn was a treasure trove for logging into accounts.
jusssi 2y ago
People are definitely running dictionaries against password hash leaks. Both examples look like they might be in a dictionary.
- coldpie 2y ago
  So what?
  - fkyoureadthedoc 2y ago
    You ask a yes/no question, someone says "yes", you say "so what?". You should have just started there. "So what if someone gets my email and password for whatever website?" So in your very specific contrived scenario that a user is using weak passwords but never reusing them, yes they are fine provided the site with the leaked account data realizes this and makes you reset your password. But we already know that in reality most people reuse weak passwords. If your reused password was a passphrase that wasn't in the dictionary and couldn't be brute forced in a reasonable time, then you would be fine.
    - coldpie 2y ago
      My point with this thread is that if you're focusing on entropy, you're wasting your time. It doesn't matter beyond some threshold, which I argue is quite low. It doesn't matter if it takes 500 years or 5000 years to crack your password, no one's doing it so long as it's beyond (say) 3 months of CPU time. It would be better to focus on easy and unique, than to focus on entropy.
      - fkyoureadthedoc 2y ago
        Yes I agree that the passwords should be unique, easy to type manually when you have the need, and some minimum threshold of entropy is nice to have. I have no idea what that minimum should be though. Aren't passwords cracked with GPU? I admittedly have no clue about this, but it sounds right to me lol. Assuming they are, a 4090 can probably guess a hell of a lot of passwords per second. I've had the same generated strong Reddit password for like 15 years, what are GPUs going to look like in the next 15? The last time I had to implement password login for something we just followed NIST guidelines and called it a day.
School-Cotton 2y ago
Low entropy means your password will be cracked if a list of password hashes leaks.
joshka 2y ago
> AFAIK basically all the auth attacks we see today are from password re-use https://haveibeenpwned.com/Passwords https://haveibeenpwned.com/Passwords says Summer2024! has been seen in two breaches, which means even if it weren't being brute forced it's less safe. 1235 has been seen significantly more times... I'm curious if you're just being satirical here - it's not entirely obvious.
- coldpie 2y ago
  I'm not. If you use a unique password for every service, entropy doesn't matter beyond a low threshold, because guessing passwords against a live service is not an attack people are actually doing. The "1235" is an extreme example, I wouldn't bet my bank account on it, but I still think the point stands.
  - ziddoap 2y ago
    >guessing passwords against a live service is not an attack people are actually doing Credential stuffing is an attack people are actually doing.
  - Terretta 2y ago
    > * guessing passwords against a live service is not an attack people are actually doing* flat wrong ... if one thinks this, one likely isn't operating a high value target
mr_toad 2y ago
> No one is out there brute-forcing passwords. They definitely are. I’ve been locked out of my own banks website twice because of people trying to guess the password too many times.
aftbit 2y ago
I had an account on an online game way back in the day with the password 12346, and it got hacked inside of 6 months.

mr_mitm 2y ago

> "Summer2024!" is perfectly fine, if you use it for exactly one service. Frankly, "1235" is probably fine. No one is out there brute-forcing passwords. Respectfully, I disagree. "Summer2024!" is probably the second password I'd try after the username itself if I have to guess a password. Use it in a password spraying attack on a company with 500 users and you will get a few hits, I promise.

coldpie 2y ago
It's a fair point, but I think my argument still stands. Guessability is a different property from entropy, yeah? "Summer1975!" has the same entropy, but you probably wouldn't have put that into your password sprayer.
- joshka 2y ago
  Summer1975! would be equally likely to be checked by a password sprayer. It has the same number of hits on HIBP, and falls into a category where heuristic password guess algorithms would generally group them as being the same thing.
nemo8551 2y ago
My old work used to give a default month-year-org name and an exclamation mark. The majority of people who still used it was insane. LinkedIn was a treasure trove for logging into accounts.

jusssi 2y ago

People are definitely running dictionaries against password hash leaks. Both examples look like they might be in a dictionary.

coldpie 2y ago
So what?
- fkyoureadthedoc 2y ago
  You ask a yes/no question, someone says "yes", you say "so what?". You should have just started there. "So what if someone gets my email and password for whatever website?" So in your very specific contrived scenario that a user is using weak passwords but never reusing them, yes they are fine provided the site with the leaked account data realizes this and makes you reset your password. But we already know that in reality most people reuse weak passwords. If your reused password was a passphrase that wasn't in the dictionary and couldn't be brute forced in a reasonable time, then you would be fine.
  - coldpie 2y ago
    My point with this thread is that if you're focusing on entropy, you're wasting your time. It doesn't matter beyond some threshold, which I argue is quite low. It doesn't matter if it takes 500 years or 5000 years to crack your password, no one's doing it so long as it's beyond (say) 3 months of CPU time. It would be better to focus on easy and unique, than to focus on entropy.
    - fkyoureadthedoc 2y ago
      Yes I agree that the passwords should be unique, easy to type manually when you have the need, and some minimum threshold of entropy is nice to have. I have no idea what that minimum should be though. Aren't passwords cracked with GPU? I admittedly have no clue about this, but it sounds right to me lol. Assuming they are, a 4090 can probably guess a hell of a lot of passwords per second. I've had the same generated strong Reddit password for like 15 years, what are GPUs going to look like in the next 15? The last time I had to implement password login for something we just followed NIST guidelines and called it a day.

School-Cotton 2y ago

Low entropy means your password will be cracked if a list of password hashes leaks.

joshka 2y ago

> AFAIK basically all the auth attacks we see today are from password re-use https://haveibeenpwned.com/Passwords https://haveibeenpwned.com/Passwords says Summer2024! has been seen in two breaches, which means even if it weren't being brute forced it's less safe. 1235 has been seen significantly more times... I'm curious if you're just being satirical here - it's not entirely obvious.

coldpie 2y ago
I'm not. If you use a unique password for every service, entropy doesn't matter beyond a low threshold, because guessing passwords against a live service is not an attack people are actually doing. The "1235" is an extreme example, I wouldn't bet my bank account on it, but I still think the point stands.
- ziddoap 2y ago
  >guessing passwords against a live service is not an attack people are actually doing Credential stuffing is an attack people are actually doing.
- Terretta 2y ago
  > * guessing passwords against a live service is not an attack people are actually doing* flat wrong ... if one thinks this, one likely isn't operating a high value target

mr_toad 2y ago

> No one is out there brute-forcing passwords. They definitely are. I’ve been locked out of my own banks website twice because of people trying to guess the password too many times.

aftbit 2y ago

I had an account on an online game way back in the day with the password 12346, and it got hacked inside of 6 months.