In “How Revolutionary Tools Cracked a 1700s Code” (New York Times, October 24, 2011), John Markoff reports on the world’s toughest codes and the design inferences used to crack them, most notably the 18th-century German Copiale cipher:
Uncertain of the original language, the researchers went down several blind alleys before following their hunches. First, they assumed the Roman characters and not the abstract symbols contained all of the information.
Eventually they concluded that the Roman letters were so-called nulls, meant to mislead the code breaker, and that the letters represented spaces between words made up of elaborate symbols. Another crucial discovery was that a colon indicated the doubling of the previous consonant.
Some codes have never been cracked.
But the white whale of the code-breaking world is the Voynich manuscript. Comprising 240 lavishly illustrated vellum pages, it has defied the world’s best code breakers. Though cryptographers have long wondered if it is a hoax, it was recently dated to the early 1400s.
But maybe not. What makes code-breaking so difficult is that the guy who wrote it may be smarter than the cryptographers.