The history of encryption is a tale of broken secrets. But some mysteries remain unraveled. Among the thousands of broken codes and ciphers solved by cryptologists from the NSA and the KGB to amateurs at home, there are the few elusive codes that no one has ever managed to crack.
What makes these ciphers even more intriguing are the people who supposedly wrote them: an estranged lover; a serial killer who sent encrypted letters in a kind of twisted mind game; an esoteric 15th century alchemist for reasons still unknown today. Some of the codes turned up in the pockets of dead men: some unidentified to this day, others who were murdered by strangers for no discernible reason why.
Some may even be hoaxes. But even figuring out which ciphers are real and which are not can be nearly insurmountable. And even if we can spot the authentic codes amidst the hoaxes, some of these rare and challenging codes may still be impossible to solve, in our lifetimes at least. We've asked Kevin Knight – the University of Southern California computer scientist
who recently helped crack the 250-year-old Copiale cipher – to walk us through seven of the most confounding codes and give us an idea of what makes these things so tough to break.
Above:
The Voynich Manuscript (1400-1500s)
Few encrypted texts are as mysterious – or as tantalizing – as the Voynich manuscript, a book dating to either 15th- or 16th-century Italy and written in a language no one understands, about a subject that no one can figure out, and involving illustrations of plants that don't exist. Plus it's got Zodiac symbols, astrological charts, illustrations of medicinal herbs, and
drawings of naked women bathing while hooked up to tubes. The manuscript's 246 calfskin pages were perhaps meant for alchemy or medieval medicine, but no one knows for sure.
What we do know is that it's written in a language distinct from any European language, and follows a pattern unique to its own. The alphabet ranges from 19 to 28 letters, with an average word length consistent with Greek- or Latin-derived languages, but is missing two-letter words while repeating words at a much higher rate than other European languages. All told, the book has 170,000 characters in it, written from left to right, and there are no punctuation marks.
William Friedman, one of the 20th century's greatest cryptographers, couldn't figure it out and suspected Voynich was a constructed, artificial language. (With no
Rosetta Stone to help translate.) German computer scientist Klaus Schmeh suspected a hoax, and also suggested the manuscript's original language could have been encoded in a much larger set of "
meaningless filler text." But there's no system for separating out the real text from the junk. Linguist and computer scientist Gordon Rugg also concluded
the manuscript was a hoax.
Knight has been wrestling with Voynich for the better part of a decade, on and off. Recently, he and University of Chicago computer scientist Sravana Reddy discovered that the
word length and frequency (.pdf) and the seeming presence of morphology – or the structure of word forms – "and most notably, the presence of page-level topics conform to natural language-like text." The problem is that no one seems to know where to go next.
Photo:
D.C.Atty/Flickr
