• Primarily0617@kbin.social
    link
    fedilink
    arrow-up
    60
    arrow-down
    2
    ·
    edit-2
    1 year ago

    you have to limit it somewhere or you’re opening yourself up for a DoS attack

    password hashing algorithms are literally designed to be resource intensive

      • Primarily0617@kbin.social
        link
        fedilink
        arrow-up
        13
        ·
        edit-2
        1 year ago

        Incorrect.

        They’re designed to be resource intensive to calculate to make them harder to brute force, and impossible to reverse.

        Some literally have a parameter which acts as a sliding scale for how difficult they are to calculate, so that you can increase security as hardware power advances.

        • confusedbytheBasics@lemmy.world
          link
          fedilink
          English
          arrow-up
          1
          ·
          1 year ago

          I was incorrect but I still disagree with you. The hashing function is not designed to be resource intensive but to have a controlled cost. Key stretching by adding rounds repeats the controlled cost to make computing the final hash more expensive but the message length passed to the function isn’t really an issue. After the first round it doesn’t matter if the message length was 10, 128, or 1024 bytes because each round after is only getting exactly the number of bytes the one way hash outputs.

            • confusedbytheBasics@lemmy.world
              link
              fedilink
              English
              arrow-up
              1
              ·
              1 year ago

              I’m a bit behind on password specific hashing techniques. Thanks for the education.

              My background more in general purpose one way hashing functions where we want to be able to calculate hashes quickly, without collisions, and using a consistent amount of resources.

              If the goal is to be resource intensive why don’t modern hashing functions designed to use more resources? What’s the technical problem keeping Argon2 from being designed to eat even more cycles?

      • andrew@lemmy.stuart.fun
        link
        fedilink
        English
        arrow-up
        3
        ·
        1 year ago

        Not true. Password hashing algorithms should be resource intensive enough to prevent brute force calculation from being a viable route. This is why bcrypt stores a salt, a hash, and the current number of rounds. That number of rounds should increase as CPUs get faster to prevent older hashes from existing in the wild which can be more effectively broken by newer CPUs.

        • confusedbytheBasics@lemmy.world
          link
          fedilink
          English
          arrow-up
          2
          ·
          1 year ago

          I was incorrect about the goal being minimal resources. I should have written that that goal was to have controlled resource usage. The salt does not increase the expense of the the hash function. Key stretching techniques like adding rounds increase the expense to reach the final hash output but does not increase the expense of the hash function. High password length allowances of several thousand characters should not lead to a denial of service attack but they don’t materially increase security after a certain length either.

          • andrew@lemmy.stuart.fun
            link
            fedilink
            English
            arrow-up
            2
            ·
            1 year ago

            I’m arguing semantics here but bcrypt is the hashing function. Per the Wikipedia article on bcrypt:

            bcrypt is a password-hashing function designed by Niels Provos and David Mazières, based on the Blowfish cipher and presented at USENIX in 1999.

            Blowfish being a symmetric encryption cipher, not a hashing function.

            Agreed on the rest, though. The hashing cost of a long password would not lead to DOS any more than the bandwidth of accepting that password etc. It’s not the bottleneck. But also no extra security beyond a point, so might as well not bother when passwords are too long.

            • confusedbytheBasics@lemmy.world
              link
              fedilink
              English
              arrow-up
              2
              ·
              1 year ago

              Semantics aside it sounds like we are in agreement. Have another upvote. :)

              Why does upvoting feel better without a karma system? shrug