5 ms·

You need to watch his video, very cool, it really helps to understand how this works: https://www.youtube.com/watch?v=f9EbD6iY9zI https://www.youtube.com/watch?

by folli 6y ago

You need to watch his video, very cool, it really helps to understand how this works: https://www.youtube.com/watch?v=f9EbD6iY9zI https://www.youtube.com/watch?v=f9EbD6iY9zI

kebman 6y ago
That video is really, really awesome! And it won't leave you feeling "Japanese" either. (Which is a great people, btw. I'd really like to go there someday, mostly for the food and language and history. And Anime also, I'm forced to admit.)
- kebman 6y ago
  You guys really need to chill out. If you've got something to say, then say it.
  - Phenomenit 6y ago
    I think you're being down-voted because your comment doesn't really add anything to the discussion at hand.
    - kebman 6y ago
      Oh, to this site punishes people for adding a positive remark. Great... I'll keep that in mind then. Anyway, thanks for letting me know!
      - Dylan16807 6y ago
        Just being positive and nothing else is what the upvote button is for. And turning your comment slightly gray is not really a punishment.
        tomhoward 6y ago
        Positive, supportive comments have always been welcome on HN.
        Dylan16807 6y ago
        Being positive and supportive is a good quality, but it is not enough to make a comment good. Comments are supposed to have thought and substance too. Shallow praise is better than a shallow dismissal, but not by enough.
        tomhoward 6y ago
        I'm pretty sure I've seen dang or pg say that quick, low-effort comments that express enthusiasm for a comment or post are fine (whereas low-effort, drive-by dismissals are very much not fine). I've tried searching but it's not obvious what search terms would turn up such a comment. But I hope my recollection about that is right. Yes we want comments to be substantive in general, but we don't want to be surly or even Grinch-like when someone is just expressing excitement and affirmation for someone else's contribution. I'm sure that's not what pg or dang would want here.
        dang 6y ago
        That's too harsh, and not in the spirit of the site. Right from the beginning, pg made this distinction: Empty comments can be ok if they're positive. There's nothing wrong with submitting a comment saying just "Thanks." What we especially discourage are comments that are empty and negative—comments that are mere name-calling. https://news.ycombinator.com/newswelcome.html https://news.ycombinator.com/newswelcome.html https://hn.algolia.com/?dateRange=all&page=0&prefix=false&query=%22empty%20comments%22%20positive&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
chias 6y ago
There's a few things in there that are factually incorrect -- in particular, the false notion that "every input has a unique output" can be quite dangerous in some cryptographic settings. That said, the purpose of this talk is about the mechanics of the function, and not its properties or how to use it safely. So don't let that detract from what is, really, an awesome presentation.
- tridentboy 6y ago
  I'm sorry, could you please elaborate? I was always under the assumption that hash functions have to be deterministic, and thus, that "every input has a unique output" was a correct statement. AFAIK the contrary is invalid, so that "not every output is the result of one and only one input".
  - apeescape 6y ago
    There are 2^256 potential outputs for SHA-256, while the number of potential inputs is infinite. Therefore, the same output can be generated with different inputs, although finding such "collisions" by chance is extremely unlikely
    - surye 6y ago
      The claim is not that every output has a unique input, which would not be correct, and seems to be what you are addressing.
      - chias 6y ago
        at 1:08 in the video, that is exactly what he claims: "So every piece of data in the world has its own unique hash digest." This is false for the reasons apeescape describes: every piece of data in the world has its own hash digest, but these hash digests are not unique.
        ChristianBundy 6y ago

by folli 6y ago

You need to watch his video, very cool, it really helps to understand how this works: https://www.youtube.com/watch?v=f9EbD6iY9zI https://www.youtube.com/watch?v=f9EbD6iY9zI

kebman 6y ago

That video is really, really awesome! And it won't leave you feeling "Japanese" either. (Which is a great people, btw. I'd really like to go there someday, mostly for the food and language and history. And Anime also, I'm forced to admit.)

kebman 6y ago
You guys really need to chill out. If you've got something to say, then say it.
- Phenomenit 6y ago
  I think you're being down-voted because your comment doesn't really add anything to the discussion at hand.
  - kebman 6y ago
    Oh, to this site punishes people for adding a positive remark. Great... I'll keep that in mind then. Anyway, thanks for letting me know!
    - Dylan16807 6y ago
      Just being positive and nothing else is what the upvote button is for. And turning your comment slightly gray is not really a punishment.
      - tomhoward 6y ago
        Positive, supportive comments have always been welcome on HN.
        Dylan16807 6y ago
        Being positive and supportive is a good quality, but it is not enough to make a comment good. Comments are supposed to have thought and substance too. Shallow praise is better than a shallow dismissal, but not by enough.
        tomhoward 6y ago
        I'm pretty sure I've seen dang or pg say that quick, low-effort comments that express enthusiasm for a comment or post are fine (whereas low-effort, drive-by dismissals are very much not fine). I've tried searching but it's not obvious what search terms would turn up such a comment. But I hope my recollection about that is right. Yes we want comments to be substantive in general, but we don't want to be surly or even Grinch-like when someone is just expressing excitement and affirmation for someone else's contribution. I'm sure that's not what pg or dang would want here.
        dang 6y ago
        That's too harsh, and not in the spirit of the site. Right from the beginning, pg made this distinction: Empty comments can be ok if they're positive. There's nothing wrong with submitting a comment saying just "Thanks." What we especially discourage are comments that are empty and negative—comments that are mere name-calling. https://news.ycombinator.com/newswelcome.html https://news.ycombinator.com/newswelcome.html https://hn.algolia.com/?dateRange=all&page=0&prefix=false&query=%22empty%20comments%22%20positive&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

chias 6y ago

There's a few things in there that are factually incorrect -- in particular, the false notion that "every input has a unique output" can be quite dangerous in some cryptographic settings. That said, the purpose of this talk is about the mechanics of the function, and not its properties or how to use it safely. So don't let that detract from what is, really, an awesome presentation.

tridentboy 6y ago
I'm sorry, could you please elaborate? I was always under the assumption that hash functions have to be deterministic, and thus, that "every input has a unique output" was a correct statement. AFAIK the contrary is invalid, so that "not every output is the result of one and only one input".
- apeescape 6y ago
  There are 2^256 potential outputs for SHA-256, while the number of potential inputs is infinite. Therefore, the same output can be generated with different inputs, although finding such "collisions" by chance is extremely unlikely
  - surye 6y ago
    The claim is not that every output has a unique input, which would not be correct, and seems to be what you are addressing.
    - chias 6y ago
      at 1:08 in the video, that is exactly what he claims: "So every piece of data in the world has its own unique hash digest." This is false for the reasons apeescape describes: every piece of data in the world has its own hash digest, but these hash digests are not unique.
      - ChristianBundy 6y ago