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Secret Agents Hold Code-Breaking Contest
Spudley writes "I just heard on the BBC that the British Government's not-so-secret code breaking organisation, GCHQ, has launched a little Christmas crypto challenge for all you budding secret agents. Should be fun to try it out... even if you're not brave enough to actually send in an entry."
it would be a good bet in my mind it will be something like what they did before (people tend to repeat themselves)so... previously on gchq
Each of the six extracts is encrypted with a simple substitution cipher. In the first extract, this is a straightforward shift: P=A, Q=B, R=C etc.
In extracts two to six, the ciphertext alphabet is formed by taking a keyword, removing those letters that occur more than once in the keyword, and then adding all remaining letters in alphabetical order. For example, in extract two, the keyword is MURDERS IN THE RUE MORGUE. By taking out those letters that are repeated in the keyword, we are left with: MURDESINTHOG. We then add all unused letters in alphabetical order to give us: MURDESINTHOGABCFJKLPQVWXYZ.
Finally, the alphabet is shifted to give the keyword PUZZLE as the encryption of A in each alphabet in turn (as read down the left hand side of the grid).
1) And Joshua the son of Nun sent two men secretly from Shittim as spies, saying, "Go, view the land, especially Jericho."
Joshua chapter 2. The Bible, c.550 BC. (An early reference to intelligence gathering.)
2) Many years ago I contracted an intimacy with a Mr. William Legrand. He was of an ancient Huguenot family, and had once been wealthy; but a series of misfortunes had reduced him to want.
Edgar Allan Poe, Tales of Mystery and Imagination: The Gold Bug. The Dollar Newspaper, Philadelphia, 1843. (The first extensive treatment of cryptanalysis in fiction.)
Keyword: MURDERS IN THE RUE MORGUE (another famous short story by Poe).
3) Holmes had been seated for some hours in silence with his long, thin back curved over a chemical vessel in which he was brewing a particularly malodorous product.
Sir Arthur Conan Doyle, The Adventure of the Dancing Men, The Strand Magazine, 1903. (Another fictional example of a substitution cipher.)
Keyword: MYCROFT HOLMES (Sherlock Holmes's brother).
4) The American handed Leamas another cup of coffee and said, "Why don't you go back and sleep? We can ring you if he shows up."
John Le Carre, The Spy Who Came In From The Cold. Victor Gollancz, 1963. (The third in the series of books featuring George Smiley, one of the best known fictional agents.)
Keyword: GEORGE SMILEY (main character in this series of books).
5) An Act to make provision about the Secret Intelligence Service and the Government Communications Headquarters, including provision for the issue of warrants and authorisations
(The Act of Parliament allowing GCHQ to operate, and defining its accountability to Parliament and the public.)
Keyword: ELIZABETH THE SECOND (signatory of the Act), Intelligence Services Act 1994.
6) On the morning of Wednesday, 15 October 1586, Queen Mary entered the crowded courtroom at Fotheringhay Castle. (Some editions of this book list the day as Saturday)
Simon Singh, The Code Book. Fourth Estate, 1999. (Singh's book is a recent tour de force on the subject of cryptography.)
Keyword: FOURTH ESTATE (publisher).
Read Bruce Schneier's Applied Cryptography, and then do all of the sample problems in the book.
(S(SKK)(SKK))(S(SKK)(SKK))
Depending on how difficult they make it, look for letters that occur often (names usually have a lot of vowels). You could use a letter histogram for that, there should be a very wide distribution of letter frequency. Then it is just a matter of spelling out the words by trial and error, until you recognise a name then plug those letters into other names, and you will eventually see more partial names to complete. Most likely the names are relativly famous, so that should be a clue. As far as relating the names to together, you are on your own.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
The have an introduction to codes and code-breaking methods on the site. Just click on the link which says "Break Some Codes" or click here.
I picked the name that looked the easiest to solve: the man's name with the apostrophe in the first column. After about 30 seconds of inspection I cam up with "Peter O'Toole." Your welcome.
FoxTrot had a comic today along those lines...