SOLVING CIPHER SECRETS Edited by M. E. Oliaver PROBABLY FOR THE FIRST TIME IN MAGAZINE HISTORY, THERE IS OFFERED HERE A BOOK CIPHER WITHOUT NAMING THE KEY WELL-SEASONED cipher, One of the first to mention it is Giovanni if centuries of service count Battista della Porta, whose " De Furtivis for anything, and yet one Literarum Notis " was published at Naples that, though cumbersome in 1563. to use, is still worthy of And Blaise de Vigenere, the French writ• consideration by virtue of er, comments at some length on it in his its relative security, is the book cipher. " Traicte des Chiffres "—Paris, 1586. That Book cipher is of the substitution class, he was well aware of its inconveniences is the substitutes usually being numbers that evidenced by the following quotation from indicate certain letters or words in certain his work. lines, paragraphs, columns, or pages of the " Now," says Vigenere, " this plan is too article, pamphlet, book, or other publication laborious, and slow in operation for business used as a key. requiring to be described in detail; it will The ways of using this cipher are too not always provide the words sought for, at numerous to mention, this being merely up least, without an immense deal of pains, to the ingenuity of those contemplating perhaps after examining through some hun• the secret correspondence. A common dred pages; and unless a dictionary be used, method is to represent each word of the the names of persons, places, or professions, message by a group of three numbers. For can be found in no book whatever. instance: 127-4-11 would indicate the /rth " Besides which," he continues, " many word of the 4th line on the 727th page of accidents may lead to a discovery of the the key volume. key or book so confided in; and many others The use of book cipher probably dates may happen to deprive us of that resource, from Gutenberg's invention, in 1450, of or to render it inconvenient to depend on printing with movable types. Previous to such a stratagem. The writing, moreover, is this time, and even up to the latter part of always liable to suspicion if intercepted," the fifteenth century, all books and all pub• Book cipher has received its share of lic and private documents in Europe were attention from writers of detective stories. wTitten by hand. And manuscript, unless Emile Gaboriau uses it effectively in his the key volume be sent along with the " Monsieur Lecoq "—first published in message, does not lend itself readily to this 1869, as also does Sir Arthur Conan Doyle kind of cipher. in " The Valley of Fear," 1914. At any rate, some of the earliest writers Gaboriau quickly disposes of the cipher on cryptography give details of the cipher. by having his detective, Lecoq, seize upon 634 FLYNN'S the only book—'' The Songs of Beranger " tionary order, that is, alphabetically, and —in the possession of his prisoner. numbered so that any term has its numeri• But in Doyle the situation is handled cal equivalent in cipher. more skillfully, for Sherlock Holmes, with This type of cipher was generally em• his customary logic, makes short work of ployed as an official and military cipher by arriving at the identity of the key volume. the English Colonies, now the United States, To outline briefly the story of the Doyle during the American Revolution. It is an cipher, Holmes receives a cryptogram, early form of code, and will be dealt with which, from its appearance, he judges must more fully in a later article. be in book cipher. Ordinary dictionary cipher may be used The cipher is from an individual who in various ways. A common method is to wants him to read the message. Therefore, represent a given word in cipher by the Holmes concludes that the key volume must word occupying the same location—cotmt- be some book that his correspondent knew ing defined words only—of the correspond• he possessed. ing column of an agreed number of pages From a number in the cipher interpret- forward or backward in the dictionary. able as a page indicator. Holmes is able to Thus, suppose that a desired word is the form some estimate of the size of this key gth word in the and column of page 63 volume. Further, by a similar inference, in the particular dictionary being used, and he decides that the book is one having two that key for encipherment is: turn forwards columns to the page.- three pages. The cipher substitutes for this Pursuing this line of reasoning, Holmes word would then be the 9th word in the 2nd narrows down the search, and finally places column of page 66. his hand on the very volume—an edition Here is an example of a cipher of this of " Whitaker's Almanack "—that his corre• kind, it being an actual message sent by a spondent had employed. Democratic agent in the electoral campaign If properly used, book cipher should be that followed the Presidential election of proof against solution without the key vol• 1876, and enciphered with an edition of ume. But to afford a maximum of diffi- Webster's Pocket Dictionary. Cipher: DUBLOON RELIQUARY YEOMAN DUCT il/fssa^'*.- Dispatch rec eive(d). Will do AUDIENCE RIGHTEOUS IF IT YEOMAN SEXTUPLE as request(ed) if it will secure SIEGE ENLIGHTEN AFTERWARDS PURLIEU, several elector(s). Act promptly. AVr.' To decipher: tttrn bach three pages. culty against unauthorized decipherment, An objection to the dictionary cipher, also different substitutes should be employed for true of the ordinary book cipher, is that repeated words of a message, and the use wanted words are not always to be found in of substitutes that represent consecutive the key volume. words in the key should be avoided. This difficulty is usually overcome by A frequently used variation of the book supplementing these ciphers with another cipher, and one mentioned above by Vi• cipher, usually of the simple substitution genere, is that employing a dictionary as type, to encipher such words. the key volume. This is commonly called Again, the ordinary dictionary does not 'dictionary cipher. contain the various grammatical inflections This should not be confused, however, of words, and consequently these termina• with the dictionnaire chiffre used in France, tions are frequently unexpressed in cipher, and elsewhere, in the eighteenth century and being determined by context. after. To illustrate this point, in the above cam• Dictionnaire chiffre consists of a specially paign cipher, RELIQUARY, RIGHTE• prepared vocabulary of letters, letter groups, OUS, and ENLIGHTEN actually repre• words, phrases, et cetera, arranged in dic- sent receive, request, and elector, respec- SOLVING CIPHER SECRETS 635 tively, in the dictionary; while the intended The principal difference here is that in forms are obviously as given in parentheses. the one instance the key volume does not Sometimes a Special cipher is used for need to be sent with the cryptogram, the these terminations. By another and rather significant terms being referred to by the transparent method, the ending of the sub• characters of the cipher; while in the other stituted word is modified to conform with case the writing used as the key must ac• that of the intended word. By this device, company the cryptogram, with the signifi• RELIQUARIED, RIGHTEOUSED, and cant letters, .syllables, or words indicated ENLIGHTENS, would have been used. by the marks. In another type of dictionary cipher, each Passing now from this general discussion word is represented by a series of numbers, of book ciphers to a particular example of indicating the page, column, and location of them, what might have been one of the most the word in tlie column. amazing uses of cipher in all history will For instance, 63-2-Q would by this meth• now be briefly related. od be interpreted as meanmg the pth word The cipher message referred to was in the and column of page 63 of the key claimed to have been intercepted during its dictionary. This variety of the cipher was transmission from a German to an .American employed during the World War by Hindus station, which was said to have communi• in this country, who were plotting with the cated it to a diplomatic agent of the former Germans for a revolution that would over• country at Washington. But as a matter of throw British rule in India. fact, the message was never sent from the As used by the brothers Lee—Arthur, German station, never was received in this Richard Henry, and William—the diction• country, and never was forvvarded to the ary cipher was extensively employed during agent at Washington. the .American Revolutionary period—the The alleged message that figured in this page being indicated by an Arabic numeral, astonishing incident was linked by the fabri• the column by a letter a or b, and the line cator of the story with the sinking of the by a Roman numeral. Lusitania. These forms of dictionary cipher are, of The cipher message was claimed to have course, open to the same objections as the originated at a great wireless station in Ger• previously described variety. But the diffi• many, and its intended destination was said culty with grammatical inflections can be to have been a certain station in this coun• relieved somewhat by using a foreign lan• try, in use at the time by German plotters to guage dictionary, such as English-German, transmit military information to their For• or English-French, where many of the in• eign Office, in violation of the neutrality of flections follow words in their definitions.