This is a repost :)
Are we really starting this shit here?
Everything on the internet is a repost. Calling it out adds nothing worthwhile to the conversation and just derails any conversation.
Yeah but when you see the same 5 posts every month it gets tiring. If the other post was in a different place though, then it’s not a repost
Infuriating fact: if a service has maximum password length limits (lower than 1000 characters), they’re reversibly storing your password and if they’re that lazy it’s probably plain text
Nope. No point in storing > 256 or even 128 chars for a password anyway. Useless storage wasted. Also it doesn’t really mean they store the password badly in the server.
Ok but are 15 characters too much?
I’ve seen 14-char limits, which are NOT reasonable
Ignoring that they must be hashed to be acceptable and that it’s not possible for 1000 characters of text to add up to a waste of storage worth mentioning in pretty much any environment, it’s literally impossible for a 128 character password limit to be beneficial in any way.
A limit below that demonstrably lowers security by a huge margin.
The length limit is mostly for the user’s sake - companies don’t want people to set their passwords to 30+ character ones that they keep forgetting and call their tech support to reset.
Couldn’t it just be that they’re using something like bcrypt which won’t take any chars above its limit into account (knowing that there’s a limit will pretty much never matter to a user but why obscure the fact)? What does it even mean to store it reversibly, just because they have a char limit doesn’t mean they are encrypting the password, could just be some frontend shenannigans as well.
Yeah, you actually better not save the users passwords in plain text or in an encrypted way it could be decrypted. You rather save a (salted) hashed string of the password. When a user logs in you compare the hashed value of the password the user typed in against the hashed value in your database.
What is hashed? Think of it like a crossfoot of a number:
Let’s say you have a number 69: It’s crossfoot is (6+9) 15. But if someone steals this crossfoot they can’t know the original number it’s coming from. It could be 78 or 87.
i was more wondering why a length limit implies anything about how they’re storing the password. once they receive the password they’re free to hash it any which way they want
random memory—yahoo back in the day used to hash the password in the browser before sending it to the server, but TLS made that unnecessary i guess
Dumb question: isn’t it irrelevant for the malicous party if it’s 78 or 87 per your example, because the login only checks the hash anyway? Won’t both numbers succesfully login?
I share your frustration, especially when the maximum password length limit is outrageously low, but they do serve a purpose.
Fun fact: Lemmy instances cap at 60. they’re not storing reversibly, they’re just using bcrypt and rather than pre-hashing the pw before bcrypt like most bcrypt users do, they just truncate to 60.
They may just base their limit on one or a few block sizes of the hash function.
That sounds incredibly unlikely. I would be good money that 99% of password length limits are not based on concrete limits. Things like “100 should be enough 🤷” must be way more common.
I doubt 1% of programmers are away of their hashes block size. It is also probably irrelevant since after the first round everything is fixed size anyways.
Best practice in 2023 is a simple, sufficiently long but memorable passphrase. Excessive requirements mean users just create weak passwords with patterns.
[Capital letter]basic word(number){special character}
Enforcing password changes doesnt help either. It just creates further patterns. The vast majority of compromised credentials are used immediately or within a short time frame anyway. Changing the password 2 months later isnt going to help and passwords like July2023!, which are common, are weak to begin with.
A non expiring, long, easily remembered passphase like
forgetting-spaghetti-toad-box
Is much more secure than a short password with enforced complexity requirements.
Drop “memorable”. 99.9% of your passwords should be managed by your password manager and don’t need to be memorized. On one or two passwords that you actually need to type (like your computer login) need to be memorable.
I am kinda paranoid about password managers. My passwords are stored somewhere on the computer, all of them, and I don’t like that idea. I can exercise my brain.
I encourage you to think critically about this and re-evaluate your decision. I would say that for at least 99.99% of people a password manager is significantly more secure overall.
- Browser-integrated password managers will avoid filling your password into the wrong site. This is a great barrier to phishing.
- Allows a unique password per-site which greatly mitigates the problem of password leaks which are fairly common.
- Allows you to use much stronger passwords than you can memorize.
- It’s quite convenient to just click “login”.
For most people phishing is a far bigger risk than some malware stealing their local password databases. To make database theft even less of a concern most password managers have the option to encrypt the local database file. This means that to steal your passwords the malware will need to extract the encryption key from the password manager process which can often be configured to forget the key quickly after the last use.
Also consider that if you have malware that can steal your password database and the encryption key it can probably just keylog all your passwords or steal your browser’s cookie jar. So the extra barrier here is minimal.
I think you are right to be suspicious of having a vault of passwords “ready to steal” but in practice the upsides far outweigh the downsides, especially if you make a security-focused choice of password manager.
I’ve been using keepassxc for a while now and it’s better than most other options, everything is stored locally and encrypted behind a master password.
All you micht want to do is make a backup of your vault onto an external drive (best practice would be encrypted via the options you have, I use luks because I’m a Linux nerd).
99.9% of your passwords should be managed by your password manager
this looks like a sensible approach until you remember password managers can be cracked, too. I’m with GP on this, a passphrase is easier to remember and is good enough for most use cases, if you need more security you should be using some form or another of 2FA anyway
forgetting-spaghetti-toad-box
I don’t know much about PW security but would a passphrase of common words not be more susceptible to dictionary attacks?
The idea is that entropy is measured with possible words instead of possible characters. It turns out 7 7-bit ascii characters have less entropy than 4 14-bit equivalent words (that is, the 16,384 most common ones). And that’s in the ideal case it’s a totally random 7 characters.
Every attack is technically a dictionary attack here, but it doesn’t help enough because the password to a computer is still 30 characters long. To a human it seems a lot easier than ")f1:.{yJCzNv]@R=S K$~= ", though.
PS. Turning /dev/random output into 7-bit ascii characters is surprisingly involved in Haskell. C would have been easier. This was the world’s slowest ninja edit.
Thanks for the explanation, I remember the explanation in https://xkcd.com/936/ but wasn’t sure how that held up for different attack methods.
Knowing that it’s already in use is.
Basically all of these constraints are bad practice, though. It’s obviously better to have a long, complex password, and not to reuse passwords between sites, but if you make shit impossible for people to remember they’re going to write it down, and a lot of people don’t use password managers (or use shared devices where they aren’t possible).
Length limits (that aren’t like 1000 characters) are unconditionally terrible practice. It means your password is probably plain text, because hashes don’t really care or take meaningfully longer based on the length of the input.
A string of (random) words is a perfectly fine password. There’s an xkcd I’m too lazy to get demonstrating it, but it genuinely does add enough randomness to break brute force.
