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A question about passwords | characters used in them (programming.dev)

submitted 2 years ago* (last edited 2 years ago) by FinancesDrone98@programming.dev to c/programming@programming.dev

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Why do so many companies and people say that your password has to be so long and complicated, just to have restrictions?

I am in the process of changing some passwords (I have peen pwnd and it’s the password I use for use-less-er sites) and suddenly they say “password may contain a maximum of 15 characters“… I mean, 15 is long but it’s nothing for a password manager.

And then there’s the problem with special characters like äàáâæãåā ñ ī o ė ß ÿ ç just to name a few, or some even won’t let you type a [space] in them. Why is that? Is it bad programming? Or just a symptom of copy-pasta?

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[–] foo@withachanceof.com 70 points 2 years ago (3 children)

Is it bad programming?

With very few exceptions, yes. There should be no restrictions on characters used/length of password (within reason) if you're storing passwords correctly.

[–] 0xSHODAN@lemmy.world 41 points 2 years ago

And if a site does have such restrictions, it could be an indication that they store passwords in plaintext, rather than hashed

[–] frezik@midwest.social 2 points 2 years ago (1 children)

Underappreciated fact: Bcrypt has a maximum of 72 bytes. It'll truncate passwords longer than that. Remember that UTF8 encoding of special characters can easily take more than one byte.

That said, this is rarely a problem in practice, except for some very long passphrases.

[–] Spzi@lemm.ee 1 points 2 years ago (1 children)

Bcrypt has a maximum of 72 bytes. It’ll truncate passwords longer than that. Remember that UTF8 encoding of special characters can easily take more than one byte.

Interesting: https://en.wikipedia.org/wiki/Bcrypt#Maximum_password_length

In the worst case a password is limited to 18 characters, when every character requires 4 bytes of UTF-8 encoding. For example:

𐑜𐑝𐑟𐑥𐑷𐑻𐑽𐑾𐑿𐑿𐑰𐑩𐑛𐑙𐑘𐑙𐑒𐑔 (18 characters, 72 bytes)

Makes me question if bcrypt deserves to be widely used. Is there really no superior alternative?

[–] janAkali@lemmy.one 2 points 2 years ago* (last edited 2 years ago)

Not only that, bcrypt could be run by GPUs and FPGA, that makes it more prone to bruteforcing attacks.

There are 2 modern alternatives: scrypt and argon2. They both require a substantial amount of memory, so gpu and hardware computation is no longer feasible.

[–] Aurenkin@sh.itjust.works 0 points 2 years ago* (last edited 2 years ago) (1 children)

A very high max of something like 500 characters just to make sure you don't get DOSed by folks hitting your endpoint with huge packets of data is about the most I would expect in terms of length restrictions. I'm not a security expert or anything though.

[–] dog@suppo.fi -1 points 2 years ago* (last edited 2 years ago)

That's a misunderstanding of DDoS. 0 byte packets are actually worse than large packets.

Which is why most DDoS (at least was) is extremely slow 0 byte requests until the server throttles/crashes under the number of requests.

E: Consider this. Are you more likely to throttle a bandwidth of terabytes/petabytes with couple million 1gb requests; or break it entirely by sending >4294967295 0 byte requests that effectively never stop being requested from the server?