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Comment on My password is not accepted because it is too long

Is the maximum 24 characters because their database column is a VARCHAR(24)? That’s one of the first questions that I thought of. Sure, it doesn’t guarantee plaintext, but it’s a indicator that it may be stored plaintext, considering hashing doesn’t care about length. Or at the very least whoever has had eyes on this code doesn’t know shit about security, which makes me less confident in the product as a whole.

The only reason I can think of to have a maximum would be to save on bandwidth and CPU cycles, and even then 24 characters is ridiculously stingy when the difference would be negligible.

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LouSlash@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago
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- spankmonkey@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
  Oh look, a free account!
  
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x00z@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
bcrypt hashes only the first 72 bytes. 24 characters is the max amount of 4 byte UTF8 characters when using bcrypt. Which is stupid because UTF8 is variable, but still, it’s a possible explanation.

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- notquitetitan@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago
  A reason reason to switch to argon :)
  
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  - WhatAmLemmy@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
    To be fair, 24 is still a secure length for a password, and will probably be for another 5+ years.
    
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Redjard@lemmy.dbzer0.com ⁨3⁩ ⁨weeks⁩ ago
Cryptographic hash functions actually have fixed runtime too, to avoid timing-based attacks.
So correct password implementations use the same storage and cpu-time regardless of the password.

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- Ziglin@lemmy.world ⁨2⁩ ⁨weeks⁩ ago
  I figured it was about the time spent transmitting. But the password should probably be hashed before sending as well as upon arrival at the server, correct?
  
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  - Redjard@lemmy.dbzer0.com ⁨2⁩ ⁨weeks⁩ ago
    It isn’t usually. If it was, the server-side function wouldn’t need a constant runtime at different-length inputs since the inputs would not have differing lengths.
    
    The problem with client-side hashing is that it is very slow (client-side code is javascript (for the forseeable future unless compatibility is sacrificed)), unpredictable (many different browsers with differing feature-sets and bugs), and timing-based attacks could also be performed in the client by say a compromised browser-addon.
    
    For transit a lot of packaging steps will round off transfer-sizes anyhow, you typically generate constant physical activity up to around 1kB. Ethernet MTU sits at ~1500 bytes for example, so a packet of 200 bytes with a 64 char password or a packet of 1400 bytes with a 1024 char password containing some emoji will time exactly identically in your local network.
    
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AA5B@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
I would have thought the opposite. I remember having a familiar conversation: “we need a sanity check in the password: what would no sane person do?” I believe we cut it off at 64 characters, but I can see someone thinking 24 is kore than enough, if they’ve never used a password generator.

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