The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography

Cryptographers have come to realize that it requires a great deal of time, effort and money to create a random key. The best random keys are created by harnessing natural physical processes, such as radioactivity, which is known to exhibit truly random behavior.

It has been argued, albeit controversially, that Bletchley Park’s achievements were the decisive factor in the Allied victory. What is certain is that the Bletchley codebreakers significantly shortened the war.

the Abbasid caliphate (or dynasty) heralded the golden age of Islamic civilization. The arts and sciences flourished in equal measure. Islamic craftsmen bequeathed us magnificent paintings, ornate carvings, and the most elaborate textiles in history, while the legacy of Islamic scientists is evident from the number of Arabic words that pepper the l

Al-Kindī’s technique, known as frequency analysis, shows that it is unnecessary to check each of the billions of potential keys. Instead, it is possible to reveal the contents of a scrambled message simply by analyzing the frequency of the characters in the ciphertext.

Besides the intolerable destruction of ships, there was also a terrible human cost-50,000 Allied seamen died during the war.

Diffie imagined two strangers meeting via the Internet, and wondered how they could send each other an encrypted message. He also considered the scenario of a person wanting to buy a commodity on the Internet. How could that person send an e-mail containing encrypted credit card details so that only the Internet retailer could decipher them? In bot

In transposition each letter retains its identity but changes its position, whereas in substitution each letter changes its identity but retains its position.

Eventually, Max Newman, a Bletchley mathematician, came up with a way to mechanize the cryptanalysis of the Lorenz cipher. Drawing heavily on Alan Turing’s concept of the universal machine, Newman designed a machine that was capable of adapting itself to different problems, what we today would call a programmable computer.

The mixed blessings of radio—ease of communication and ease of interception—were brought into sharp focus at the outbreak of the First World War. All sides were keen to exploit the power of radio, but were also unsure of how to guarantee security. Together, the advent of radio and the Great War intensified the need for effective encryption.