Another recent challenge, issued by the Defense Advanced Research Projects Agency (Darpa), was aimed at identifying new methods to assemble shredded documents — or potential vulnerabilities in the military’s current document shredding practices. It was structured as a race to win $50,000 and it drew 9,000 registered teams. The winner — the ‘All Your Shreds Are Belong to U.S.’ team — pieced together five documents that were shredded into more than 10,000 pieces in 33 days using a combination of computer algorithms and human assembly.