The Code Book

It would seem that cryptography is a venture for the more mathematically oriented among us. How refreshing to read a book that shows how important historic events have relied on (well, more or less) normal people to break the most difficult codes. Here are stories of heroism and stupidity, and sometimes it is more a lesson in culture than in science.

Richly illustrated, the book takes the reader from ancient times to modern days. Some of the code techniques found in the book are sure to remind you about games children play. For example, take the straightforward Caesar Shift Cipher, where the alphabet is simply shuffled to the left or right to produce unintelligible text. But breaking this code is a simple matter of matching words and phrases, as is well described in the book.

There are many ways to encrypt a text. The problem is usually the decryption. The recipient of the message must know how the text has been encrypted; in other words, he needs the key. The problem of key distribution has often struck severe blows to otherwise excellent encryption techniques. For instance, if you need to send encrypted messages to army leaders out in the field, how can you make sure that it can be read by all of them? And how do you avoid having the code cracked by the enemy?

The age of computers and electronic communication has opened up new possibilities. The popular encryption technique used on the Internet, PGP (Pretty Good Privacy), has shown that it is possible for anyone to send secret messages across the web. But this is (of course) causing grey hairs on the heads of bureaucrats, who seek new ways to gain insight into other people’s matters.

Perhaps the strongest aspect of this book is the way each story turns into a thriller. This is a true page-turner; you just have got to find out how a given code was cracked, and who did it. The historical events that are described take on real life. Truly excellent is the chapter on how the team at Bletchley Park, with the presence of master-mind Alan Turing, cracked the infamous Enigma Code used by the Germans in World War II.

Interestingly, modern quantum cryptography opens up a possibility for unbreakable codes. By using photons as information packets, it is impossible to intercept a code without either ruining it or revealing your presence to the reader. This marvellous technique seems like magic, but in fact it is beginning to see the light of day in experiments.

As a matter of interest, Mr Singh offers a reward of $10,000 to the first person who breaks the ten coded messages in the book. Although it was deemed almost impossible by some, the code was recently cracked by a Swedish team. This does not in any way reduce the value of this book, and it is safe to say that Simon Singh has again proven that he is a master of the art of composing popular science literature.

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