5 ms·

Meh. Buy three ebooks from different accounts, render them to pain text, diff them and take out the differences. Why three? The assumption is 2 books would ha

by columbo 13y ago

Meh. Buy three ebooks from different accounts, render them to pain text, diff them and take out the differences. Why three? The assumption is 2 books would have the correct value and 1 book would have the copyrighted value. Though I don't see this as DRM. I've done this before on a much smaller scale to track things as they enter the wild. It's just security through obscurity, the digital equivalent of a tracking collar without any of the benefits, like guaranteed uniqueness. It's also crazy overkill. Here's a much simpler way to do it: At the end of every period randomly decide to add an extra space. Hardly noticeable. Spread (again random) between 1024 and 2048 of these over the entire document. Count them up... now you have a pretty decent identifier without having to do any sort of special logic to the words themselves. To the average person it's not noticeable, it doesn't require messing with the original document, and it can be made unique enough to be a digital fingerprint. Of course this house of cards falls apart when you know the secret.

lqdc13 13y ago
There would probably be a few things different. I think the different things could just be replaced by a new different thing. For ex if the words are synonyms, auto-replace it by another synonym. Same with punctuation. But now you need something like 3 books instead of 1. So they succeeded in a sense.
marme 13y ago
why even bother with this? just randomly change punctuation the same way drm is and they wont be able to match it with the correct account
- drchiu 13y ago
  That was my first thought as well. Whoever came up with this idea may have more countermeasures, however. For instance, every page may provide a unique enough punctuational fingerprint to identify the buyer.
- jerf 13y ago
  They know where to look. You don't. You'll be throwing up a lot of chaff in places they aren't looking in the hopes of catching where they are looking in the crossfire, which is an approach that will lead to a degraded book. You can mutate the hell out of the paragraph I just typed, but if you don't know that the only bit I've hidden in that paragraph was "chaff" vs. "noise", you may not hit a thing that I'm looking for. And bear in mind that's two short sentences; if they hide enough of these things in there, they'll have plenty of leftover bits to track you down. columbo's idea is much more solid. It directly identifies the changes, and while it's not even all that challenging to put enough bits into these books to identify which 3 books the pirate copy comes from[1], you are making much greater strides towards defeating the DRM. And if you learn enough from the comparisons to begin reverse-engineering the algorithm, you may be able to entirely defeat it. ("Aha, they always treat "fire" and "flames" as one bit, I'll just use the same one all the time." String enough of those together and you win.) By the way, to any who might question whether students would do this... I used to work on a learning content management system primarily used for highly randomized physics problems. It is absolutely staggering what students will do to cheat. They'll happily generate Excel spreadsheets fully exploring 48 permutations of a problem, each of which may be missing a random 2 out of 5 variables to be solved for, and share it far and wide. Though whether the utility of "not being caught pirating" rises to the level of "hope to score with members of the desirable sex by helping them cheat through a mandatory class" (the only possible motivation I can imagine for some of what we saw) is dubious. [1]: In fact I'd consider it an obvious elaboration to also fingerprint other information into the books, such as destination University, and so on. Basically you're encoding a bit string into the books; you can do all the usual things you do with such bit strings, like parity, encoding various bits of information, etc. It's just steganography being put to a new use, and we know that can encode arbitrary information with arbitrary characteristics.
clicks 13y ago
Not to mention... would-be pirates could just use a non-traceable method of payment when acquiring these eBooks. This seems to be a lot of effort for really no good.
- andrewflnr 13y ago
  It's probably not that much effort. It seems like the hardest part is picking unobtrusive flex points.
- visarga 13y ago
  > would-be pirates could just use a non-traceable method of payment when acquiring these eBooks. what? since when do digital 'pirates' pay for ebooks?
  - a_bonobo 13y ago
    The very first element of the chain of distribution still has to acquire the original somehow.
    - clicks 13y ago
      Exactly. A lot of leakers in the scene actually go to quite some lengths (financially and otherwise) to be the first one to release something. It's a whole another world of its own where cred matters a lot, and people will really do go through a lot to make their name known.
      - tekromancr 13y ago
        Scene culture is fascinating.
        a_bonobo 13y ago
        There used to be a selfmade low budget series called The Scene which showed the internal workings of release groups: http://www.welcometothescene.com/faq.html http://www.welcometothescene.com/faq.html I watched 2 episodes or so before it became too boring watching people chat on AIM, but I learned quite a bit about the internals (in how far these are true, I do not know - the makers say it's fictional but the stories are authentic)

by columbo 13y ago

lqdc13 13y ago

There would probably be a few things different. I think the different things could just be replaced by a new different thing. For ex if the words are synonyms, auto-replace it by another synonym. Same with punctuation. But now you need something like 3 books instead of 1. So they succeeded in a sense.

marme 13y ago

why even bother with this? just randomly change punctuation the same way drm is and they wont be able to match it with the correct account

drchiu 13y ago
That was my first thought as well. Whoever came up with this idea may have more countermeasures, however. For instance, every page may provide a unique enough punctuational fingerprint to identify the buyer.
jerf 13y ago
They know where to look. You don't. You'll be throwing up a lot of chaff in places they aren't looking in the hopes of catching where they are looking in the crossfire, which is an approach that will lead to a degraded book. You can mutate the hell out of the paragraph I just typed, but if you don't know that the only bit I've hidden in that paragraph was "chaff" vs. "noise", you may not hit a thing that I'm looking for. And bear in mind that's two short sentences; if they hide enough of these things in there, they'll have plenty of leftover bits to track you down. columbo's idea is much more solid. It directly identifies the changes, and while it's not even all that challenging to put enough bits into these books to identify which 3 books the pirate copy comes from[1], you are making much greater strides towards defeating the DRM. And if you learn enough from the comparisons to begin reverse-engineering the algorithm, you may be able to entirely defeat it. ("Aha, they always treat "fire" and "flames" as one bit, I'll just use the same one all the time." String enough of those together and you win.) By the way, to any who might question whether students would do this... I used to work on a learning content management system primarily used for highly randomized physics problems. It is absolutely staggering what students will do to cheat. They'll happily generate Excel spreadsheets fully exploring 48 permutations of a problem, each of which may be missing a random 2 out of 5 variables to be solved for, and share it far and wide. Though whether the utility of "not being caught pirating" rises to the level of "hope to score with members of the desirable sex by helping them cheat through a mandatory class" (the only possible motivation I can imagine for some of what we saw) is dubious. [1]: In fact I'd consider it an obvious elaboration to also fingerprint other information into the books, such as destination University, and so on. Basically you're encoding a bit string into the books; you can do all the usual things you do with such bit strings, like parity, encoding various bits of information, etc. It's just steganography being put to a new use, and we know that can encode arbitrary information with arbitrary characteristics.

clicks 13y ago

Not to mention... would-be pirates could just use a non-traceable method of payment when acquiring these eBooks. This seems to be a lot of effort for really no good.

andrewflnr 13y ago
It's probably not that much effort. It seems like the hardest part is picking unobtrusive flex points.
visarga 13y ago
> would-be pirates could just use a non-traceable method of payment when acquiring these eBooks. what? since when do digital 'pirates' pay for ebooks?
- a_bonobo 13y ago
  The very first element of the chain of distribution still has to acquire the original somehow.
  - clicks 13y ago
    Exactly. A lot of leakers in the scene actually go to quite some lengths (financially and otherwise) to be the first one to release something. It's a whole another world of its own where cred matters a lot, and people will really do go through a lot to make their name known.
    - tekromancr 13y ago
      Scene culture is fascinating.
      - a_bonobo 13y ago
        There used to be a selfmade low budget series called The Scene which showed the internal workings of release groups: http://www.welcometothescene.com/faq.html http://www.welcometothescene.com/faq.html I watched 2 episodes or so before it became too boring watching people chat on AIM, but I learned quite a bit about the internals (in how far these are true, I do not know - the makers say it's fictional but the stories are authentic)