A review of "The Code Book", by Simon Singh.

History is punctuated with codes. From ancient Rome to Cyberspace, countless battles and intrigues have turned on secure communication, or want of it. Mary, Queen of Scots lost her head to Queen Elizabeth’s code-breakers; World War II might have been lost or prolonged by years but for England’s successful cryptanalytic effort; in our own time, the potential fortunes of Internet commerce depend largely on the robust encryption of financial transactions.

Secret codes are at the center of some of history’s juiciest stories. But in order to fully appreciate the drama, you have to wade into some pretty deep thinking. Cryptography, that most critical human artifice, does not yield to casual conversation. All but the most superficial discussions require a solid understanding of linguistics, statistics, number theory, and any number of more obscure disciplines. And that’s a pity; a rich trove of historical romance is concealed behind the daunting technical detail.

Which is why Simon Singh’s new book is such a welcome addition to the literature on the topic. In “The Code Book”, not only does he expertly guides the audience through the cryptological quagmire, but he makes the journey an enjoyable one as well.

That the topic yields so readily to Singh’s touch should come as no surprise; after all, he’s the same author who brought us “Fermat’s Enigma” – another numerically sticky tale he improbably wove into a best-seller – in which he so lucidly explained the mathematician Andrew Wiles’ 1993 proof of Fermat’s last theorem – acheived some 350 years after Fermat proposed it. Singh has a rare talent for reducing complexity into engaging, bite-sized narratives. In fact, there are large stretches of his new book where the reader might forget entirely that the topic at hand is also essentially higher math, instead experiencing it as an entertaining, fascinating history.

In addition to recounting the major epics in the cryptological record – Charles Babbage and the difference engine, the Enigma code machine, Alan Turing and Bletchley Park – the text is richly peppered with less significant, but highly engaging historical curios that serve to ground and humanize the topic: Victorian mash-notes encrypted for publication in the era’s prudish classified ads; the dot-cipher technique which enabled thrifty Victorians to send a personal letter for the (much cheaper) price of posting a newspaper; King Philip II of Spain who, miffed with the compromise of this imperial codes, petitioned the Vatican that the offending code-breaker’s triumphs could only be explained by a partnership with the forces of evil.

It’s also a history filled with fascinating characters. History’s great cryptographers, as it turns out, are a highly idiosyncratic bunch: linguists, bridge fanatics, rogue classicists, chess scholars, and crossword addicts, all marked conspicuously by eccentricities and oddball habits. Students of computer culture will also recognize them as the forerunners of today’s quirky digital elite – proto-nerds, if you will.  Certainly this phenomenon was not lost on Winston Churchill who, after a visit with the Bletchley Park recruits, remarked to the head of the Secret Intelligence Service, “I told you to leave no stone unturned, but I didn’t expect you to take me so literally.”

“Cryptography will provide the locks and keys of the Information Age.” Singh’s historical instincts seem particularly acute here. In 1999, a comprehensive overview of cryptography is particularly timely; as we move into the age of ubiquitous networking, it is a field that – once of interest only to mathematicians, linguists, and intelligence agencies – is rapidly becoming important to anyone with a modem and a credit card. The history of cryptography should also be of critical interest to computing enthusiasts; largely because of the advent of solid-state computing devices, it seems we’re living in the golden age of cryptography. Over its 2000-plus year history, most the really great advances and developments (Diffie-Helmann public key encryption, the fabled RSA algorithms, the populist, government-threatening PGP) have been made in the last few decades.

The final chapter of this book is also a somewhat startling futurist text. Until now, the history of cryptography has been a contest of leap-frog between the code-makers and code-breakers, one in turn trumping the other with ever-cleverer techniques. If Simon Singh has really done his homework – and I suspect he has – it appears this epoch of cryptological jousting is drawing to a close. Quantum cryptography – a technique already validated in the laboratory – will forever castrate the cryptanalyst’s art, courtesy of Heisenberg’s uncertainty principle. In this new world of perfect secrecy, it is quantum mechanics, not mathematical algorithms, that stand between the code-breaker and the encoded secrets. To compromise quantum encryption, the cryptanalyst must first blow away modern Physics – not an encouraging prospect for even the most dedicated spy. Which means that “The Code Book” may, in historical retrospect, be the first book to achieve closure, completely encircling its topic.

Set amid the appendices of "The Code Book" is the Cipher Challenge, in which the author sets ten ciphertexts as challenges to readers itching to test their cryptanalytic mettle. The prize is an audacious $15,000. Though I have no inclination to try, Unix users will be interested to note that two of the ciphers contain uuencoded blocks – a cunning ploy to drag the digerati into the chase.

Some readers may find, as I did, that extra measures of attention and persistence are required for some of the book’s more technical passages. I do not begrudge Simon Singh the extra effort. It is a miracle, given the subject matter, that he succeeds at all for a popular audience. Making this stuff comprehensible to the rest of us is in itself a notable public service. That he also succeeds in entertaining is an unexpected pleasure.