3 ms·

How do they compute a hash of a file without actually looking at the file? Magic?

deleted 13y ago
[deleted]
Dylan16807 13y ago
'looking' here means having a person look at the file or possibly having a system run analysis* of the file. Neither happens. Since you seem to be talking about having their systems touch any bytes of the file, I have a more important question: How would you expect to have a file synced with dropbox and shared via dropbox without dropbox touching the bytes? Magic? * you know what I mean by analysis, think gmail
- TheLoneWolfling 13y ago
  Simple. Truecrypt (or whatever other encrypted filesystem you prefer) volume on Dropbox. Files in partition. Dropbox has no idea what is on the volume. (In an ideal world, you'd have a filesystem set up that was a separate encrypted file for each file in the virtual filesystem, with an additional encrypted file that contained the virtual directory info. But this is simpler.)
  - wdewind 13y ago
    How would the file get to the truecrypt volume? Wouldn't it be significantly more expensive to run the app on encrypted hdd?
  - Dylan16807 13y ago
    Well sure if you use another program to encrypt the file then Dropbox can only see the encrypted bytes, but that's not what mbrutsch was objecting to. A particular truecrypt volume could still have a takedown related to it.
    - TheLoneWolfling 13y ago
      Not automatically via the method used here (hash blacklist)
      - Dylan16807 13y ago
        When I say 'particular' I mean someone notices the truecrypt volume being shared either semi-publicly or multiple times and files a DMCA for the volume itself. Then you have to alter it or make a new one.
- mbrutsch 13y ago
  > 'looking' here means having a person look at the file or possibly having a system run analysis* of the file. Neither happens. I know that, and you know that, but I showed this article to my wife (who is a casual computer user), and while she understood the difference when explained, she said that as a non-techie, she interpreted the title differently. If you hash my data, and take action based on that hash, then you have looked at the data, however cursory or algorithmic it may have been. FWIW, I had this same discussion on reddit, where it devolved instantly into name-calling. HN is much more civil. Thanks for that.
  - Dylan16807 13y ago
    Did she realize that this was a file already uploaded to Dropbox? That's a very important distinction in my mind. Dropbox has already calculated hashes and fed the data to the servers at that point. They don't don't do any 'looking' beyond the data-shoveling process. It's the DMCA sharing check that avoids 'looking' even in the most pedantic sense, not the overall use of Dropbox.
PhasmaFelis 13y ago
Simple! By redefining "not looking" to mean "totally looking, but in a way that we've decided doesn't count."

deleted 13y ago

[deleted]

'looking' here means having a person look at the file or possibly having a system run analysis* of the file. Neither happens. Since you seem to be talking about having their systems touch any bytes of the file, I have a more important question: How would you expect to have a file synced with dropbox and shared via dropbox without dropbox touching the bytes? Magic? * you know what I mean by analysis, think gmail

TheLoneWolfling 13y ago
Simple. Truecrypt (or whatever other encrypted filesystem you prefer) volume on Dropbox. Files in partition. Dropbox has no idea what is on the volume. (In an ideal world, you'd have a filesystem set up that was a separate encrypted file for each file in the virtual filesystem, with an additional encrypted file that contained the virtual directory info. But this is simpler.)
- wdewind 13y ago
  How would the file get to the truecrypt volume? Wouldn't it be significantly more expensive to run the app on encrypted hdd?
- Dylan16807 13y ago
  Well sure if you use another program to encrypt the file then Dropbox can only see the encrypted bytes, but that's not what mbrutsch was objecting to. A particular truecrypt volume could still have a takedown related to it.
  - TheLoneWolfling 13y ago
    Not automatically via the method used here (hash blacklist)
    - Dylan16807 13y ago
      When I say 'particular' I mean someone notices the truecrypt volume being shared either semi-publicly or multiple times and files a DMCA for the volume itself. Then you have to alter it or make a new one.
mbrutsch 13y ago
> 'looking' here means having a person look at the file or possibly having a system run analysis* of the file. Neither happens. I know that, and you know that, but I showed this article to my wife (who is a casual computer user), and while she understood the difference when explained, she said that as a non-techie, she interpreted the title differently. If you hash my data, and take action based on that hash, then you have looked at the data, however cursory or algorithmic it may have been. FWIW, I had this same discussion on reddit, where it devolved instantly into name-calling. HN is much more civil. Thanks for that.
- Dylan16807 13y ago
  Did she realize that this was a file already uploaded to Dropbox? That's a very important distinction in my mind. Dropbox has already calculated hashes and fed the data to the servers at that point. They don't don't do any 'looking' beyond the data-shoveling process. It's the DMCA sharing check that avoids 'looking' even in the most pedantic sense, not the overall use of Dropbox.

PhasmaFelis 13y ago

Simple! By redefining "not looking" to mean "totally looking, but in a way that we've decided doesn't count."