Shredding may not be as secure as we thought.
As this thestar.com article relates, an "E-Puzzler" pattern-recognition machine reassembles the pieces of documents that the East German STASI sought to destroy in the waning days of communist East Germany. Their shredding machines broke down, and when they tried to burn the documents instead, the local citizens broke in and stopped them, so they set about doing it by hand. But of course, they only got so far.
Yes, the E-Puzzler has other uses, so far, in helping Chinese archaeologists reconstruct smashed Terracotta warriors found in the tomb of Emperor Qin.
In addition to the article below, here is a link to a PBS interview on the topic.