Simon Singh’s The Code Book proves, once again, that he is a superlatively skilled writer on technical and scientific subjects. Thanks to his book, I now actually understand how Enigma worked and how it was broken: likewise, the Vigenere Cipher that has been built into this site for so long. This book manages to capture both major reasons for which cryptography is so fascinating: the technical aspects, centred around the ingenuity of the methods themselves, and the historical dramas connected, from the execution of Mary Queen of Scots to the use of ULTRA intelligence during the Second World War.
Anybody who has any interest in code-making or code-breaking should read this book, unless they already know so much about the subject as to make Singh’s clear and comprehensible explanations superfluous. Even then, it may arm them with valuable tools for explaining interesting concepts to the less well initiated.
At the end of the book is a series of ten ciphers for the reader to break. Originally, there was a Â£15,000 prize for the first person to crack the lot. Now, they exist for the amusement of amateur cryptologists. I doubt very much I will get through all ten, but I am giving it a try. The first ciphertext is on his website and is helpfully labeled ‘Simple Monoalphabetic Substitution Cipher.’ I expect to crack it quickly.
[Update: Six minutes later] I’ve got it:
in the same hour came forth fingers of a manâ€™s hand, and wrote over against the candlestick upon the plaster of the wall of the kingâ€™s palace; and the king saw the part of the hand that wrote. then the kingâ€™s countenance was changed, and his thoughts troubled him, so that the joints of his loins were loosed, and his knees smote one against another. the king cried aloud to bring in the astrologers, the chaldeans, and the soothsayers. and the king spake, and said to the wise men of babylon, whosoever shall read this writing, and show me the interpretation thereof, shall be clothed with scarlet, and have a chain of gold about his neck, and shall be the third ruler in the kingdom. then came in all the kingâ€™s wise men; but they could not read the writing, nor make known to the king the interpretation thereof. then was king belshazzar greatly troubled, and his countenance was changed in him, and his lords were astonished. now the queen, by reason of the words of the king and his lords, came into the banquet house; and the queen spake and said, o king, live forever; let not thy thoughts trouble thee, nor let thy countenance be changed; there is a man in thy kingdom, in whom is the spirit of the holy gods; and in the days of thy father light and understanding and wisdom, like the wisdom of the gods, was found in him; whom the king nebuchadnezzar thy father, the king, i say, thy father, made master of the magicians, astrologers, chaldeans, and soothsayers; forasmuch as an excellent spirit, and knowledge, and understanding, interpreting of dreams, and showing of hard sentences, and dissolving of doubts, were found in the same daniel, whom the king named belteshazzar; now let daniel be called, and he will show the interpretation. the first codeword is othello
[Update: 14 August 2007] I have been at it for less than a day and I have already solved the three easiest ciphers: 1, 2, and 4. I will give 3 a try next.