Is it possible to reassemble a shredded document?

Answers to your questions about the news.
July 31 2009 7:14 AM

Unshreddable

How to reassemble a shredded document.

Shredded documents.
Shredded documents 

Federal prosecutors told a judge last week that they have started reassembling documents shredded by the Stanford Financial Group, whose owner, R. Allen Stanford, is charged with running a $7 billion Ponzi scheme. How do you reconstruct documents after they've been passed through a shredder?

With a computer. In a typical reconstruction process, technicians feed all the available shreds into a scanner. An automated software program then assigns a unique ID to each piece and analyzes a number of characteristics, including size, color, indentation, and font. Using a matching algorithm, the software then identifies potential neighboring shreds, displaying them onscreen for an operator to confirm. (For the home user, an Israeli company sells software that can turn any PC and scanner into an "unshredder.")

Advertisement

Not all shredded documents can be put back together. The possibility and ease of reconstruction depends on the size of the shreds—the smaller and more numerous the pieces, the harder it is to reconstruct a document. Strip shredders cut paper into long strips 1/8- to 5/16-inch wide and are the most popular option because of their speed and low cost—but they're also the easiest to reassemble since they produce a relatively small number of large fragments. Cross-cut shredders, which slice paper into many tiny, confettilike pieces, are significantly more secure (and expensive), while shredders that pulverize paper into dust cost thousands of dollars but are essentially reconstruction-proof. (To secure top-secret information, the Department of Defense requires that the majority of shredded particles "not exceed 5 square millimeters.") When using a strip-shredder, the slicing direction also has implications for reconstruction. Horizontal cuts may leave entire lines of text intact. Vertical shredding, which ensures that sentences are broken up, is more secure.

Before advances in scanning and computer technology, documents had to be reconstructed by hand. Assuming all the pieces are in one place, reassembling a shredded document is a bit like solving a jigsaw puzzle; the reconstructionist must painstakingly sift through the shreds, looking for matches. During the 1979 Iranian Revolution, students and militants who took over the U.S. Embassy in Tehran turned to local carpet weavers to reassemble classified CIA documents they found that had been shredded. These pages were later published in a set of about 60 volumes called Documents From the U.S. Espionage Den. And in 2002, former FBI agent William Daly took about an hour to reassemble a shredded page from the dictionary on Good Morning America.

Got a question about today's news? Ask the Explainer.

Explainer thanks William Daly of Control Risks Group, Bob Johnson of the National Association for Information Destruction, and Andrew Glassner.

Adrian Chen is a freelance writer and an editor at The New Inquiry.

TODAY IN SLATE

Politics

Don’t Worry, Obama Isn’t Sending U.S. Troops to Fight ISIS

But the next president might. 

The Extraordinary Amicus Brief That Attempts to Explain the Wu-Tang Clan to the Supreme Court Justices

Amazon Is Officially a Gadget Company. Here Are Its Six New Devices.

The Human Need to Find Connections in Everything

It’s the source of creativity and delusions. It can harm us more than it helps us.

How Much Should You Loathe NFL Commissioner Roger Goodell?

Here are the facts.

Altered State

The Plight of the Pre-Legalization Marijuana Offender

What should happen to weed users and dealers busted before the stuff was legal?

Surprise! The Women Hired to Fix the NFL Think the NFL Is Just Great.

You Shouldn’t Spank Anyone but Your Consensual Sex Partner

Moneybox
Sept. 17 2014 5:10 PM The Most Awkward Scenario in Which a Man Can Hold a Door for a Woman
  News & Politics
Altered State
Sept. 17 2014 11:51 PM The Plight of the Pre-Legalization Marijuana Offender What should happen to weed users and dealers busted before the stuff was legal?
  Business
Business Insider
Sept. 17 2014 1:36 PM Nate Silver Versus Princeton Professor: Who Has the Right Models?
  Life
Outward
Sept. 17 2014 6:53 PM LGBTQ Luminaries Honored With MacArthur “Genius” Fellowships
  Double X
The XX Factor
Sept. 17 2014 6:14 PM Today in Gender Gaps: Biking
  Slate Plus
Slate Fare
Sept. 17 2014 9:37 AM Is Slate Too Liberal?  A members-only open thread.
  Arts
Brow Beat
Sept. 17 2014 8:25 PM A New Song and Music Video From Angel Olsen, Indie’s Next Big Thing
  Technology
Future Tense
Sept. 17 2014 9:00 PM Amazon Is Now a Gadget Company
  Health & Science
Medical Examiner
Sept. 17 2014 11:48 PM Spanking Is Great for Sex Which is why it’s grotesque for parenting.
  Sports
Sports Nut
Sept. 17 2014 3:51 PM NFL Jerk Watch: Roger Goodell How much should you loathe the pro football commissioner?