

DARPA: Shredder Challenge Solved.  See images from the winning entry. - petedoyle
http://www.shredderchallenge.com

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masukomi
Why are they all straight shreds? Bad guys don't know how to go to Staples.com
and buy a Diamond shredder? Sure, it's useful to be able to decode those but
if you're going to throw $50,000 on the table why not at least ask for
something slightly more sophisticated than aligning what are essentially
rectangles.

I wouldn't be surprised if someone out there makes a cheap consumer grade
shredder with some shape more obnoxious than diamonds too...

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GHFigs
_Bad guys don't know how to go to Staples.com and buy a Diamond shredder?_

Staples.com doesn't actually carry diamond-cut shredders. At least, none that
I can find.

The smallest shred size I _can_ find there is 3.175mm x 9.525 mm. By
comparison, the document in the fifth puzzle is taken from a legal pad (8.7 mm
line spacing), and the shreds are only a little bit longer. Would the shape
really make that much of a difference at this scale?

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adrianN
I'm no expert, but I'd say having shreds for which the orientation is not as
obvious makes the problem much harder. Add to that the amount of work
necessary to get a clean image of the thousands of particles a page
produces...

Amazon sells relatively cheap security level 4, and rather expensive security
level 6 shredders.

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chr15
I'm really interested in seeing the algorithms and implementation behind the
solutions.

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otaviogood
The third place guy posted an explanation of his algorithms here:
[http://www.marcnewlin.com/2011/12/you-should-probably-
start-...](http://www.marcnewlin.com/2011/12/you-should-probably-start-
burning-your_02.html) I was on the winning team and we have been writing up
our algorithms too. Hopefully we'll be able to post them soon.

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Tichy
I supose I can save the money for a new shredder now. Home incinerators for
the rescue?

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minus1
This is not a solved problem by any means. I finished in the top ten, and most
competitive teams used a combination of image processing for chad suggestion
and brute force. It required hundreds of man hours to reassemble just a
handful of documents under controlled conditions.

Imagining a real-life scenario of dozens or hundreds of documents mixed
together in a shredder bin makes my head hurt.

So, I wouldn't worry too much about your shredded docs just yet.

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DanBC
I guess that the use of sensitive documents rules out Mechanical Turk or a
game version for the real work, but I'd be interested to see what turkers
could do.

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minus1
One team used a crowd sourced "game" method with some success. They had
thousands of people register, and were able to solve the first few problems
quickly, but they began to stall on the more complex puzzles.

I was surprised to find that this method doesn't scale well when the puzzle
reaches a certain size.

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dhughes
I'd be impressed if they could reassemble a shreded CD or DVD.

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DisasterPlan
Burn all your shredding Write with invisible ink (lemon juice, ACME Brand ,
etc...) Small font, tight spacing.

;-)

