CRYPTOGRAPHY

If Napoleon had had better passwords, you might be reading this in French today.

Computers may be new, historically speaking, but cryptography is as old as writing. Martin, a British professor of information security who wrote one of the standard texts on the topic, Everyday Cryptography, delivers numerous examples of failed codes from the past, including one that cost Julius Caesar dearly and another that essentially sent Napoleon packing to Saint Helena. On the matter of that Napoleonic code, Martin writes that it was “designed to counter frequency analysis” by blending plain text letters into “ciphertext” along with “masking common letter combinations using dummy characters.” As with much that is technological, operator error ruined a good thing: The soldiers entrusted with the job encrypted only parts of the French military’s communications, and the British soon decoded “La Grande Chiffre de Paris.” Every code will eventually be broken, and passwords like “password” and “god123” are going to be cracked in a second. In this survey, Martin gives readers the essentials of cryptography without much by way of the underlying numbers even though cryptography is, strictly speaking, a branch of mathematics. Even though “you can breeze through life using cryptography without even being aware of it,” courtesy of the algorithms hidden away on your bank site and in your smartphone, it’s better to know a little about the devices and formulas by which messages go from one place to another without being intercepted and decoded. The author’s text, while readable and indeed even elementary at times (“ASCII…defines the rules for switching between keyboard characters and bits”), requires a high tolerance for nerdspeak and the ability to deal with terms such as “transport layer security” and “challenge-response” without immediately dozing off. Regardless, it’s highly informative and offers a good argument for hardening one’s digital security.

Tech-savvy readers will come away with a greater appreciation for the science involved in keeping secrets from prying eyes.