5 ms·

This might even have an application for real documents. There are police cases where some suspects have tried to destroy evidence. Manually reconstructing the o

This might even have an application for real documents. There are police cases where some suspects have tried to destroy evidence. Manually reconstructing the original takes a lot of effort. I expect that the CIA and NSA already have software for it, but I have never heard of it being used in a police case.

perihelions 5y ago
Germany has run a program for decades to recover the Stasi's paper documents, the bulk of which it shredded at the fall of the GDR. People can sometimes get their own Stasi files, if they're recovered. https://www.dw.com/en/how-ai-could-solve-a-600-million-piece-puzzle/av-55130523 https://www.dw.com/en/how-ai-could-solve-a-600-million-piece... https://www.wired.com/2008/01/ff-stasi/ https://www.wired.com/2008/01/ff-stasi/ https://boingboing.net/2018/01/09/truth-reconciliation-and-tape.html https://boingboing.net/2018/01/09/truth-reconciliation-and-t... Surprisingly, there's never been an HN thread about this (as far as I can tell). From the Wired link: "Today, the study in Poppe's Berlin apartment is lined floor to 12-foot ceiling with bookshelves full of volumes on art, literature, and political science. But one shelf, just to the left of her desk, is special. It holds a pair of 3-inch-thick black binders — copies of the most important documents in Poppe's secret police files. This is her Stasi shelf."
- odysseus 5y ago
  The painstaking process to put back together shredded Stasi documents is mentioned at the end of The Lives of Others: https://www.imdb.com/title/tt0405094/ https://www.imdb.com/title/tt0405094/ Great movie, by the way.
  - airstrike 5y ago
    _Fantastic_ movie, I just wanted to add.
  - einpoklum 5y ago
    I really didn't like that movie, focusing on people who are wholly uninteresting politically; presenting a sort of a "shocked and chagrined" attitude to people being spied on by the government; and treating West Germany as some sort of paradise. I would recommend Ken Loach's Fatherland instead; but - only until when Dritterman arrives in the UK (the end of the film is kind of messed up).
    - CamperBob2 5y ago
      The political class is more than capable of looking after itself, thanks. It's the common people who have the most to fear, and the movie does a great job at underscoring that very point.
      - einpoklum 5y ago
        The Lives of Others's protagonist is a celebrated playwright, not a "common person"...
ampdepolymerase 5y ago
Current office shredders are almost all capable of double shredding but considering how easy it is to reverse by OP's project, it may be necessary to implement further measures for document destruction. A laser or enzymic based method could work but neither are particularly office-friendly.
- jhayward 5y ago
  OP's method relies on the permutation of elements in (columns or rows) to be in the same order for each (column or row). If you're just handed a pile of confetti you don't have that same correspondence.
  - wongarsu 5y ago
    Also, you generally have written correspondence, not images. I doubt that the similarity metric of OPs method produces reasonable results on text, and a good similarity metric for text would be much more complicated. On the other hand physical shredders typically have other weaknesses, for example if you don't stir the shredded result you have a high correlation between original the current and original relative position of the individual pieces.
    - aliasEli 5y ago
      With written text, you would expect that at least some the letters from one shred would continue on its neighbors. I don't see why the similarity metric would not work. Also normally you have a pretty high contrast between the letter and the background, unlike the image that was used in the example.
      - jhgb 5y ago
        If you have a language model, then sequences of characters appearing in your text will add further information to your edge matches.
- deleted 5y ago
  [deleted]
jpalomaki 5y ago
DARPA ran a competition on this problem around 10 years ago [1] and page from Darpa archive [2] [1] https://en.wikipedia.org/wiki/DARPA_Shredder_Challenge_2011 https://en.wikipedia.org/wiki/DARPA_Shredder_Challenge_2011 [2] https://archive.darpa.mil/shredderchallenge/index.html https://archive.darpa.mil/shredderchallenge/index.html

perihelions 5y ago

Germany has run a program for decades to recover the Stasi's paper documents, the bulk of which it shredded at the fall of the GDR. People can sometimes get their own Stasi files, if they're recovered. https://www.dw.com/en/how-ai-could-solve-a-600-million-piece-puzzle/av-55130523 https://www.dw.com/en/how-ai-could-solve-a-600-million-piece... https://www.wired.com/2008/01/ff-stasi/ https://www.wired.com/2008/01/ff-stasi/ https://boingboing.net/2018/01/09/truth-reconciliation-and-tape.html https://boingboing.net/2018/01/09/truth-reconciliation-and-t... Surprisingly, there's never been an HN thread about this (as far as I can tell). From the Wired link: "Today, the study in Poppe's Berlin apartment is lined floor to 12-foot ceiling with bookshelves full of volumes on art, literature, and political science. But one shelf, just to the left of her desk, is special. It holds a pair of 3-inch-thick black binders — copies of the most important documents in Poppe's secret police files. This is her Stasi shelf."

odysseus 5y ago
The painstaking process to put back together shredded Stasi documents is mentioned at the end of The Lives of Others: https://www.imdb.com/title/tt0405094/ https://www.imdb.com/title/tt0405094/ Great movie, by the way.
- airstrike 5y ago
  _Fantastic_ movie, I just wanted to add.
- einpoklum 5y ago
  I really didn't like that movie, focusing on people who are wholly uninteresting politically; presenting a sort of a "shocked and chagrined" attitude to people being spied on by the government; and treating West Germany as some sort of paradise. I would recommend Ken Loach's Fatherland instead; but - only until when Dritterman arrives in the UK (the end of the film is kind of messed up).
  - CamperBob2 5y ago
    The political class is more than capable of looking after itself, thanks. It's the common people who have the most to fear, and the movie does a great job at underscoring that very point.
    - einpoklum 5y ago
      The Lives of Others's protagonist is a celebrated playwright, not a "common person"...

ampdepolymerase 5y ago

Current office shredders are almost all capable of double shredding but considering how easy it is to reverse by OP's project, it may be necessary to implement further measures for document destruction. A laser or enzymic based method could work but neither are particularly office-friendly.

jhayward 5y ago
OP's method relies on the permutation of elements in (columns or rows) to be in the same order for each (column or row). If you're just handed a pile of confetti you don't have that same correspondence.
- wongarsu 5y ago
  Also, you generally have written correspondence, not images. I doubt that the similarity metric of OPs method produces reasonable results on text, and a good similarity metric for text would be much more complicated. On the other hand physical shredders typically have other weaknesses, for example if you don't stir the shredded result you have a high correlation between original the current and original relative position of the individual pieces.
  - aliasEli 5y ago
    With written text, you would expect that at least some the letters from one shred would continue on its neighbors. I don't see why the similarity metric would not work. Also normally you have a pretty high contrast between the letter and the background, unlike the image that was used in the example.
    - jhgb 5y ago
      If you have a language model, then sequences of characters appearing in your text will add further information to your edge matches.
deleted 5y ago
[deleted]

jpalomaki 5y ago

DARPA ran a competition on this problem around 10 years ago [1] and page from Darpa archive [2] [1] https://en.wikipedia.org/wiki/DARPA_Shredder_Challenge_2011 https://en.wikipedia.org/wiki/DARPA_Shredder_Challenge_2011 [2] https://archive.darpa.mil/shredderchallenge/index.html https://archive.darpa.mil/shredderchallenge/index.html