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The Cracking Code Book

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Язык: Английский
Год издания: 2018 год
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      The Cracking Code Book
Simon Singh

How to make it, break it, hack it, crack it.The secret history of codes and code breaking.Simon Singh’s best-selling title The Code Book now re-issued for the young-adult market.The Science of Secrecy from Ancient Egypt to Quantum Cryptography.Simon Singh brings life to an amazing story of puzzles, codes, languages and riddles – revealing the continual pursuit to disguise and uncover, and to work out the secret languages of others.Codes have influenced events throughout history, both in the stories of those who make them and those who break them. The betrayal of Mary Queen of Scots and the cracking of the enigma code that helped the Allies in World War II are major episodes in a continuing history of cryptography. In addition to stories of intrigue and warfare, Simon Singh also investigates other codes, the unravelling of genes and the rediscovery of ancient languages and most tantalisingly, the Beale ciphers, an unbroken code that could hold the key to a $20 million treasure.

SIMON SINGH

the

cracking

codebook

How to

make it,

break it,

hack it,

crack it.

To the Teachers and Mortals

who took the time to inspire me

XICYIQKMHR, VOIR RFH LKRQT

The urge to discover secrets is deeply ingrained in human nature; even the least curious mind is roused by the promise of sharing knowledge withheld from others. Some are fortunate enough to find a job which consists in the solution of mysteries, but most of us are driven to sublimate this urge by the solving of artificial puzzles devised for our entertainment. Detective stories or crossword puzzles cater for the majority; the solution of secret codes may be the pursuit of a few.

John Chadwick

The Decipherment of Linear B

Contents

Cover (#u530ed9a4-09de-5d66-ba26-ff45a4a878bf)

Title Page (#ua1864704-2fce-58e8-beec-e7a09044124a)

Introduction (#u1788f819-8ceb-5fb9-bc7c-90c07aebb379)

1 The Cipher of Mary Queen of Scots (#u1a75907c-51c2-5921-80ca-66580704cebc)

2 The Anonymous Codebreaker (#uaa687717-15ff-5c0e-bd23-0da9d5a50401)

3 The Mechanization of Secrecy (#litres_trial_promo)

4 The Language Barrier (#litres_trial_promo)

5 Alice and Bob Go Public (#litres_trial_promo)

6 Pretty Good Privacy (#litres_trial_promo)

The Codebreaker’S Challenge (#litres_trial_promo)

Appendix A (#litres_trial_promo)

Appendix B (#litres_trial_promo)

Appendix C (#litres_trial_promo)

Appendix D (#litres_trial_promo)

Appendix E (#litres_trial_promo)

Acknowledgements (#litres_trial_promo)

Further Reading (#litres_trial_promo)

Index (#litres_trial_promo)

About The Author (#litres_trial_promo)

Also By Simon Singh (#litres_trial_promo)

Copyright (#litres_trial_promo)

About the Publisher (#litres_trial_promo)

Introduction (#ulink_1a5baa3c-7fed-59c0-8d46-782a0293934b)

For centuries, kings, queens and generals have relied on efficient communication in order to govern their countries and command their armies. At the same time, they have all been aware of the consequences of their messages falling into the wrong hands, revealing precious secrets to rival nations and betraying vital information to opposing forces. It was the threat of enemy interception that motivated the development of codes and ciphers: techniques for disguising a message so that only the intended recipient can read it.

The desire for secrecy has meant that nations have operated codemaking departments, which were responsible for ensuring the security of communications by inventing and implementing the best possible codes. At the same time, enemy codebreakers have attempted to break these codes and steal secrets. Codebreakers are linguistic alchemists, a mystical tribe attempting to conjure sensible words out of meaningless symbols. The history of codes and ciphers is the story of the centuries-old battle between codemakers and codebreakers, an intellectual arms race that has had a dramatic impact on the course of history.

In writing The Cracking Code Book, I have had two main objectives. The first is to chart the evolution of codes. Evolution is a wholly appropriate term, because the development of codes can be viewed as an evolutionary struggle. A code is constantly under attack from codebreakers. When the codebreakers have developed a new weapon that reveals a code’s weakness, then the code is no longer useful. It either becomes extinct or it evolves into a new, stronger code. In turn, this new code thrives only until the codebreakers identify its weakness, and so on. This is similar to the situation facing, for example, a strain of infectious bacteria. The bacteria live, thrive and survive until doctors discover an antibiotic that exposes a weakness in the bacteria and kills them. The bacteria are forced to evolve and outwit the antibiotic, and if successful, they will thrive once again and re-establish themselves.

History is punctuated with codes. They have decided the outcomes of battles and led to the deaths of kings and queens. I have therefore been able to call upon stories of political intrigue and tales of life and death to illustrate the key turning points in the evolutionary development of codes. The history of codes is so inordinately rich that I have been forced to leave out many fascinating stories, which in turn means that my account is not definitive. If you would like to find out more about your favourite tale or your favourite codebreaker, then I would refer you to the list of further reading.

Having discussed the evolution of codes and their impact on history, the books second objective is to demonstrate how the subject is more relevant today than ever before. As information becomes an increasingly valuable commodity, and as the communications revolution changes society, so the process of encoding messages, known as encryption, will play an increasing role in everyday life. Nowadays our phone calls bounce off satellites and our emails pass through various computers, and both forms of communication can be intercepted with ease, so jeopardizing our privacy. Similarly, as more and more business is conducted over the Internet, safeguards must be put in place to protect companies and their clients. Encryption is the only way to protect our privacy and guarantee the success of the digital marketplace. The art of secret communication, otherwise known as cryptography, will provide the locks and keys of the Information Age.

However, the public’s growing demand for cryptography conflicts with the needs of law enforcement and national security. For decades, the police and the intelligence services have used wiretaps to gather evidence against terrorists and organized crime syndicates, but the recent development of ultrastrong codes threatens to undermine the value of wiretaps. The forces of law and order are lobbying governments to restrict the use of cryptography, while civil libertarians and businesses are arguing for the widespread use of encryption to protect privacy. Who wins the argument depends on which we value more, our privacy or an effective police force. Or is there a compromise?

Before concluding this introduction, I must mention a problem that faces any author who tackles the subject of cryptography: the science of secrecy is largely a secret science. Many of the heroes in this book never gained recognition for their work during their lifetimes because their contribution could not be publicly acknowledged while their invention was still of diplomatic or military value. This culture of secrecy continues today, and organizations such as the U.S. National Security Agency still conduct classified research into cryptography. It is clear that there is a great deal more going on of which neither I nor any other science writer is aware.

Figure 1 Mary Queen of Scots.

1 The Cipher of Mary Queen of Scots (#ulink_7013cad5-2eea-51c8-8e1a-826bde80bb37)

The birth of cryptography, the substitution cipher and the invention of codebreaking by frequency analysis

On the morning of Saturday, October 15, 1586, Queen Mary entered the crowded courtroom at Fotheringhay Castle. Years of imprisonment and the onset of rheumatism had taken their toll, yet she remained dignified, composed and indisputably regal. Assisted by her physician, she made her way past the judges, officials and spectators, and approached the throne that stood halfway along the long, narrow chamber. Mary had assumed that the throne was a gesture of respect towards her, but she was mistaken. The throne symbolized the absent Queen Elizabeth, Mary’s enemy and prosecutor. Mary was gently guided away from the throne and towards the opposite side of the room, to the defendant’s seat, a crimson velvet chair.

Mary Queen of Scots was on trial for treason. She had been accused of plotting to assassinate Queen Elizabeth in order to take the English crown for herself. Sir Francis Walsingham, Elizabeth’s principal secretary, had already arrested the other conspirators, extracted confessions and executed them. Now he planned to prove that Mary was at the heart of the plot, and was therefore equally to blame and equally deserving of death.

Walsingham knew that before he could have Mary executed, he would have to convince Queen Elizabeth of her guilt. Although Elizabeth despised Mary, she had several reasons for being reluctant to see her put to death. Firstly, Mary was a Scottish queen, and many questioned whether an English court had the authority to execute a foreign head of state. Secondly, executing Mary might establish an awkward precedent – if the state is allowed to kill one queen, then perhaps rebels might have fewer reservations about killing another, namely Elizabeth. Finally, Elizabeth and Mary were cousins, and their blood tie made Elizabeth all the more squeamish about ordering the execution. In short, Elizabeth would sanction Mary’s execution only if Walsingham could prove beyond any hint of doubt that she had been part of the assassination plot.

The conspirators were a group of young English Catholic noblemen intent on removing Elizabeth, a Protestant, and replacing her with Mary, a fellow Catholic. It was apparent to the court that Mary was a figurehead for the conspirators, but it was not clear that she had given her blessing to the conspiracy. In fact, Mary had authorized the plot. The challenge for Walsingham was to demonstrate a clear link between Mary and the plotters.

On the morning of her trial, Mary sat alone in the dock, dressed in sorrowful black velvet. In cases of treason, the accused was forbidden counsel and was not permitted to call witnesses. Mary was not even allowed secretaries to help her prepare her case. However, her plight was not hopeless, because she had been careful to ensure that all her correspondence with the conspirators had been written in cipher. The cipher turned her words into a meaningless series of symbols, and Mary believed that even if Walsingham had captured the letters, he could have no idea of the meaning of the words within them. If their contents were a mystery, then the letters could not be used as evidence against her. However, this all depended on the assumption that her cipher had not been broken.

Unfortunately for Mary, Walsingham was not merely principal secretary, but also England’s spymaster. He had intercepted Mary’s letters to the plotters, and he knew exactly who might be capable of deciphering them. Thomas Phelippes was the nations foremost expert on breaking codes, and for years he had been deciphering the messages of those who plotted against Queen Elizabeth, thereby providing the evidence needed to condemn them. If he could decipher the incriminating letters between Mary and the conspirators, then her death would be inevitable. On the other hand, if Mary’s cipher was strong enough to conceal her secrets, then there was a chance that she might survive. Not for the first time, a life hung on the strength of a cipher.

THE EVOLUTION OF SECRET WRITING

Some of the earliest accounts of secret writing date back to Herodotus – “the father of history”, according to the Roman philosopher and statesman Cicero. In The Histories, Herodotus chronicled the conflicts between Greece and Persia in the fifth century BC, which he viewed as a confrontation between freedom and slavery, between the independent Greek states and the oppressive Persians. According to Herodotus, it was the art of secret writing that saved Greece from being conquered by Xerxes, the despotic leader of the Persians.

The long-running feud between Greece and Persia reached a crisis soon after Xerxes began constructing a city at Persepolis, the new capital for his kingdom. Tributes and gifts arrived from all over the empire and neighbouring states, with the notable exceptions of Athens and Sparta. Determined to avenge this insolence, Xerxes began mobilizing a force, declaring that “we shall extend the empire of Persia such that its boundaries will be God’s own sky, so the sun will not look down upon any land beyond the boundaries of what is our own.” He spent the next five years secretly assembling the greatest fighting force in history, and then, in 480 BC, he was ready to launch a surprise attack.
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