Cryptography has been a tool largely used by governments to avoid their communications being read by the enemy or other unfriendly states, but historically it has also been utilized by individuals to protect their more questionable or taboo activities from discovery.
This battle is presented in the book as a rather bipolar trend; cryptographers trying to protect data and crypt-analysts trying to discover the meaning of that data. I found this to be slightly misleading. The representation of the history of the field as a constant struggle between two distinct parties does make for a more entertaining read, and adds an element of conflict by conjuring images of an ancient and continual intellectual game, but in reality these two groups are often one and the same.
Whilst I admit that the race to develop stronger codes and ciphers was in many ways separate from the race to break them, they were also inextricably linked, and undertaken by the same people. One has to allow a certain amount of poetic license in popular science books, especially in this case, as it has lightened what could have been a dry topic.
The way in which the book is structured allows a complete novice access. Starting from the first discoveries in cryptography and working forward chronologically, whilst explaining the method behind the discoveries, educates the reader in basic technique without effort. One reads a fascinating historical account, and later realizes that they now have a good understanding of the mathematical concepts behind these approaches they've been reading of.
The book places these techniques into context, giving historical examples of their use. Often they are revealed to have played large and important parts in famous events, ranging from wars and political plots, to events which are not even strictly related to cryptography.
For example it is shown how crypt-analytic approaches were utilized in the deciphering of ancient languages such as hieroglyphics. These languages are dead, in that there are no living individuals who have the ability to read them, and no information was available to help in their deciphering. By studying the frequency of letters or symbols in the text, as when attempting to break a cipher, it was possible to slowly read meaning into the text, and map the alphabet.
Many of these scripts were decrypted by amateur crypt-analysts, rather than academics. One point the author makes is that there are still many that remain a mystery, such as the Etruscan and Indus scripts. One has to wonder whether a book like this, combined with the current national fixation with puzzles such as Soduko, would create a resurgence in interest, and lead to some of these being broken.
One interesting point that the book makes is that the vast majority of work performed by cryptographers is done in secret, largely for security agencies all over the world, and that this has been true for some time. Therefore it is not uncommon for crypt-analysts to receive no recognition for their work, or to have a discovery attributed to them long after their death. These organizations must classify the work in the interest of national security, so in a way this book stands as an anonymous tribute to their cunning and multidisciplinary talent.
Examples from the book of such discoveries include Charles Babbage breaking the Vigenere cipher in 1854, which only came to light in the 1970s. The author suggests that the work was kept secret to aid the Royal Navy, as it occurred just after the Crimean War started. The credit for the discovery instead fell to a retired Prussian army officer who independently discovered it in 1863.
This is shown to be one of the enduring themes of the story of cryptography, leading right through to the 1970s where credit for developing the RSA cryptographic technique went to Diffie, Hellman and Merkle in 1975, despite being developed in 1969 at GCHQ, a fact that was only publicly admitted in 1997.
A section of the book that will be of particular appeal to computer scientists is where cryptography is shown to have given birth to computing. Born from the desire for a method to perform simple operations on numbers very quickly. Computers now dominate the field of cryptography and crypt-analysis, and their ability to perform a task millions of times with no errors has transformed the science. It is also noted how much we rely on cryptography daily, in areas such as e-commerce, where our details are encrypted without us even being aware of the fact.
The final chapter is an examination into the politics of cryptography, and a balanced look into the ethical implications of governmental snooping on communication, versus the possible benefits of reducing serious crime and terrorism. This is clearly a very pertinent point in todays political climate, and a balanced look at this issue is a very valuable thing. With the heightened risk of terrorist attack, or at least the public perception of such, the government are intercepting more and more communications for analysis, and encryption by criminals is becoming more and more popular.
The book covers the topic well; from governmental use, to anecdotes about lovers exchanging secret messages. Throughout this the reader is constantly being eased into the mathematical technique behind, in a manner that does not require a background in mathematics. There is an appendix to the book, in the form of 5 cipher challenges for the reader to attempt to crack. The knowledge gleaned from the book should be preparation enough to do so, and will fascinate the curious nature of the books audience.
Matthew Sparkes' is a journalist and programmer, his homepage is Non-Tech City."
You can purchase The Science of Secrecy from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.