A code that stumped Thomas Jefferson and other cryptologists for over two centuries has finally been cracked, the Wall Street Journal reports. The cipher—sent to Jefferson in 1801 by mathematician Robert Patterson as an example of the perfect code—piqued the interest of defense cryptologist Lawren Smithline, who tackled the jumble of letters using methods available in the 19th century, although sped up with the help of computers.
Smithline broke down the code, which Patterson had boasted would remain uncracked until the end of time, into two-letter segments and analyzed 19th-century speeches for clues. After weeks of work, he discovered that the encoded message was the beginning of the Declaration of Independence—which was partially authored by Jefferson himself. "Patterson played this little joke on Thomas Jefferson," says Smithline. "And nobody knew until now."