The Mathematics of Reassembling Shredded Documents

Factual Questions
1

Back during the Carter Administration, when Iranian radicals were about to overrun the U.S. Embassy, American intelligence officers inside the compound were feverishly shredding sensitive documents in their “vault.” Apparently, they succeeded–or at least thought they had–until news reports months later revealed that the radicals had meticulously reassembled many of the shredded documents to learn the classified secrets therein.

It seems there would be a mathematical means of speeding up the reassembly of shredded documents. For instance, could one code the printed lines of shredded text (from top to bottom in terms of relative position on the shredded paper) and then use a computer to cross-match everything and thereby reassemble it much faster? (After all, when you straight-cut shred a document, the word fragments are kept in order relative to their position on the page.)

Sorry if I did not explain this well, but I’m hoping you get my drift. ALSO, let’s ignore shredded documents that are cut in a criss-cross pattern and instead focus on the conventional (1970s-era) method of straight-cut shredding.

thanks.

2

Actually, it’s pretty easy to reassemble shredded documents by hand, at least the straight-cut shredding method. A google search on shredded puzzle reassemble turned up the classic document on this topic as the very first link:

THE ART OF RECONSTRUCTING SHREDDED DOCUMENTS WORKING WITH PAPER SPAGHETTI

Arjuna34

3

I recall reading a paper by IBM scientists back in the early 1970s that described a project to catalog all known pottery and fresco fragments in every museum in the world. The program “played jigsaw puzzle” with hundreds of thousands of fragments, and even managed to connect several pieces of a broken fresco with another piece in other museums across the world.
So yeah, there are ways to do this. But it isn’t necessarily practical. I recall reading a story about one bank that accidentally shredded a batch of incoming checks for processing. They hired temps to sort the checks and try to tape them all together. They started by sorting the paper strips by color. That’s sorta how these computer programs work.