The Code Book

Yash Agarwal

The Code Book

I was interested in Cryptography and Number Theory during my undergraduate studies so reading the history of Cryptography in this book was intriguing for me. The author has done excellent work in making sure that even an uninitiated person in Cryptography can understand and appreciate the importance of work done in this field. The people unequipped with the necessary background knowledge will enjoy this book as much as the math nerds. The book contains very little mathematical stuff, but the author tries to explain the ciphers by taking appropriate examples.

I enjoyed the story of the breaking of the Enigma Machine. It seems to be a perfect time to watch The Imitation Game. 😄 The book gets boring in the post RSA part. Probably one reason behind this was my lack of knowledge about Quantum Computing. Although a few days back, two of my colleagues were discussing an idea about Quantum Computing. I overheard their discussion, and surprisingly, I was able to understand everything they were talking, to some extent. So I guess that this book has at least initiated me to the field of Quantum Computing.

It was a 5-star book for me, and it has reserved its place in my favorite books shelf. I will revisit this book in future when I get a chance to teach Cryptography to someone. Before that, I need to learn Cryptography, right! Anyone reading this review, if you have any recommendations for books on Cryptography and Number Theory, please do comment.

Here are some of my favorite quotes from the book (not in any particular order):

  1. It has been said that the First World War was the chemists’ war, because mustard gas and chlorine were employed for the first time, and that the Second World War was the physicists’ war, because the atom bomb was detonated. Similarly, it has been argued that the Third World War would be the mathematicians’ war, because mathematicians will have control over the next great weapon of war — information.

  2. The only people who are in a position to point out my errors are also those who are not at liberty to reveal them.

  3. How to conceal a message within a hard-boiled egg by making an ink from a mixture of one ounce of alum and a pint of vinegar, and then using it to write on the shell. The solution penetrates the porous shell, and leaves a message on the surface of the hardened egg albumen, which can be read only when the shell is removed.

  4. The security of a cryptosystem must not depend on keeping secret the crypto-algorithm. The security depends only on keeping secret the key.

  5. A man is crazy who writes a secret in any other way than one which will conceal it from the vulgar.

  6. A code is defined as substitution at the level of words or phrases, whereas a cipher is defined as substitution at the level of letters. Hence the term encipher means to scramble a message using a cipher, while encode means to scramble a message using a code. Similarly, the term decipher applies to unscrambling an enciphered message, and decode to unscrambling an encoded message. The terms encrypt and decrypt are more general, and cover scrambling and unscrambling with respect to both codes and ciphers.

  7. I wish to God these calculations had been executed by steam! - Charles Babbage

  8. Nothing should be as favorably regarded as intelligence; nothing should be as generously rewarded as intelligence; nothing should be as confidential as the work of intelligence. - Sun Tzu

  9. Adversity is one of the foundations of successful codebreaking.

  10. The Polish success in breaking the Enigma cipher can be attributed to three factors: fear, mathematics and espionage.

  11. It’s about right and wrong. In general terms. It’s a technical paper in mathematical logic, but it’s also about the difficulty of telling right from wrong. People think—most people think—that in mathematics we always know what is right and what is wrong. Not so. Not any more.

  12. The way to get to the top of the heap in terms of developing original research is to be a fool, because only fools keep trying. You have idea number 1, you get excited, and it flops. Then you have idea number 2, you get excited, and it flops. Then you have idea number 99, you get excited, and it flops. Only a fool would be excited by the 100th idea, but it might take 100 ideas before one really pays off. Unless you’re foolish enough to be continually excited, you won’t have the motivation, you won’t have the energy to carry it through. God rewards fools.

  13. Mixing yellow and blue paint to make green paint is a one-way function because it is easy to mix the paint, but impossible to unmix it. Another one-way function is the cracking of an egg, because it is easy to crack an egg but impossible then to return the egg to its original condition. For this reason, one-way functions are sometimes called Humpty Dumpty functions.

  14. The easiest way to understand the concept of a two-way function is in terms of an everyday activity. The act of turning on a light switch is a function, because it turns an ordinary lightbulb into an illuminated lightbulb. This function is two-way because if a switch is turned on, it is easy enough to turn it off and return the light-bulb to its original state.

  15. An existence theorem shows that a particular concept is possible, but is not concerned with the details of the concept.

  16. We cannot know, as a matter of principle, the present in all its details.

  17. Propose to an Englishman any principle, or any instrument, however admirable, and you will observe that the whole effort of the English mind is directed to find a difficulty, a defect, or an impossibility in it. If you speak to him of a machine for peeling a potato, he will pronounce it impossible: if you peel a potato with it before his eyes, he will declare it useless, because it will not slice a pineapple. - Charles Babbage

  18. Cryptanalysis could not be invented until a civilization had reached a sufficiently sophisticated level of scholarship in several disciplines, including mathematics, statistics, and linguistics. The Muslim civilization provided an ideal cradle for cryptanalysis, because Islam demands justice in all spheres of human activity, and achieving this requires knowledge, or ilm. Every Muslim is obliged to pursue knowledge in all its forms, and the economic success of the Abbasid caliphate meant that scholars had the time, money, and materials required to fulfil their duty. They endeavoured to acquire knowledge of previous civilizations by obtaining Egyptian, Babylonian, Indian, Chinese, Farsi, Syriac, Armenian, Hebrew and Roman texts and translating them into Arabic. In 815, the Caliph of Ma’mun established in Baghdad the Bait al-Hikmah (‘House of Wisdom’), a library and centre for translation.

Cheers 😄

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