Top News, Articles, and Interviews in Philosophy

Codes and Ciphers

Philosophy News image
My book group recently read a 2017 mystery called The Lost Book of the Grail by Charlie Lovett. In the novel, an English bibliophile and an American digitizer track down a mysterious book thought to lead to the Holy Grail. The chief clue: a secret message hidden in the rare books collection of the fictional Barchester Cathedral Library. The message is a complex polyalphabetic substitution cipher that can only be solved by finding key words hidden in the books. Coded messages are common plot devices, used not just by Dan Brown but also by Edgar Allan Poe, Sir Arthur Conan Doyle, Jules Verne, Dorothy Sayers, Agatha Christie, and Neal Stephenson, among many others. Aficionados distinguish among codes and ciphers. They also talk about steganography, which involves hiding messages, sometimes covertly as in a microdot and sometimes in plain sight as when the first letters of the paragraphs of a text spell out a word. Aficionados also refer to anagrams, which are expression made up by rearranging the letter (or numbers) of another expression. My name, for example, anagrams as BATTLED WAISTLINE. There is also a distinction between codes and ciphers. A code is a technique for rendering one set of meanings using other, usually shorter, symbols. In early Morse Code telegraphy, for example, a word in the code book could be used to stand for a whole sentence or phrase, enabling efficient messaging. Stenographers and journalists use shorthand and the US Secret Service uses code names for its protectees—like Lancer (for JFK) and Rawhide (for Ronald Reagan). Ciphers refer to messages which are systematically altered by some algorithm, such as replacing one symbol for another. Cryptography refers to both ciphers and codes. How do ciphers work? The classic example is one called the Caesar shift. This is an encryption in which each character is replaced by one a certain number of places down the alphabet. Julius Caesar’s encrypted messages were said to use a shift of three characters. . .

Continue reading . . .

News source: Linguistics – OUPblog

blog comments powered by Disqus