Code Breaking by Rudolph Kippenhahn, Constable, 拢20, ISBN 0094798907
The Code Book by Simon Singh, Fourth Estate, 拢16.99, ISBN 1857028791
SPARE a thought for German astrophysicist Rudolph Kippenhahn, whose history of cypher-makers and breakers, Code Breaking, has been translated into English, only to find itself trounced in every respect by Simon Singh鈥檚 longer, more ambitious, and far more readable opus, The Code Book. 鈥淲hen I heard that my book would also be published in the English-speaking world, I was overcome with joy,鈥� Kippenhahn enthuses, through translator Ewald Osers. (It may be Osers鈥� unhappy efforts that gave Kippenhahn鈥檚 prose its antique patina.)
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Kippenhahn rounds up the usual suspects: from Caesar鈥檚 habit of shifting all his letters along a few places to create a simple, monoalphabetic cypher (so A becomes, say, D, B becomes E, and so on); through the breaking of the German Enigma codes during the Second World War; to today鈥檚 debates about the merits of public-key cryptography. This allows anyone to use a public key to encrypt a message so that only the intended recipient can read it.
In passing, he reflects upon the codes we come across in everyday life, including the numerological niceties of credit cards and International Standard Book Numbers. He reflects also on our tendency to invent order out of chaos, recalling how, in 1941, the US government harassed a hapless advertising manager, whose illustration of a dice game in The New Yorker happened to predict the date of the attack on Pearl Harbour.
This reflects the enduring, shameful appeal of cypher work. No matter how complex they become, however full of dead ends and nonsense passages, cyphers are nonetheless human documents.
Intellectually demanding but philosophically trivial, cyphers offer the historian little meat beyond themselves鈥攁 Boy鈥檚 Own narrative of cryptological creation and ultimately collapse. Perhaps this is why Singh makes a very welcome detour into archaeology. His account of the deciphering of the ancient Cretan script Linear B is a keen reminder鈥攊n the midst of a cogent and entertaining book鈥攐f his formidable reputation among popularisers of mathematics and science.
Once the preserve of literary scholars, cryptography has fallen to mathematicians, and Singh accords both traditions due respect. He is also politically canny, and it is good to see him pick apart some of the more alarmist scenarios bandied about over the Internet concerning public key cryptography.
Today, effectively unbreakable cyphers are ours for the taking, but criminals are quick to exploit such cyphers, and governments may make them illegal. Singh sees nothing new in this heated and rather portentous debate. 鈥淭here is no reason why we cannot change our policy [towards encryption] to suit the political, economic and social climate,鈥� he says. 鈥淭he deciding factor will be whom the public fears the most鈥攃riminals or the government.鈥� He does, however, conclude that codemakers will finally win over codebreakers, by creating absolutely unbreakable cyphers.
This is all down to quantum cryptography, a technique for transmitting a message using photons of different polarities. Any attempt to observe signals irrevocably alters the polarity of many photons, and destroys the message before it can ever be read. There is something undeniably dizzying and millennial about such technology.
But Singh鈥檚 enthusiasm for cryptography is such that he is never tempted to overstate the importance of cryptography in the wider world. What if codemakers do, finally, win their centuries-old battle with code-breakers? Perhaps we should heed the words of American cryptographer Whitfield Duffie, whom Singh quotes in his final pages.
鈥淚n the 1790s,鈥� Duffie writes, 鈥渨hen the Bill of Rights was ratified, any two people could have a private conversation鈥攚ith a certainty no one in the world enjoys today鈥攂y hiding in the bushes. There were no recording devices, parabolic microphones, or laser interferometers bouncing off their eyeglasses. You will note that civilisation survived.鈥�