A pack of cards is sometimes made the vehicle of a cipher, in this manner. The parties determine, in the first place, upon certain arrangements of the pack. For example: it is agreed that, when a writing is to be commenced, a natural sequence of the spots shall be made; with spades at top, hearts next, diamonds next, and clubs last. This order being obtained, the writer proceeds to inscribe upon the top card the first letter of his epistle, upon the next the second, upon the next the third, and so on until the pack is exhausted, when, of course, he will have written fifty-two letters. He now shuffles the pack according to a preconcerted plan. For example: he takes three cards from the bottom and places them at top, then one from top, placing it at bottom, and so on, for a given number of times. This done, he again inscribes fifty-two characters as before, proceeding thus until his epistle is written. The pack being received by the correspondent, he has only to place the cards in the order agreed upon for commencement, to read, letter by letter, the first fifty-two characters as intended. He has then only to shuffle in the manner pre-arranged for the second perusal, to decipher the series of the next fifty-two letters—and so on to the end. The objection to this cryptograph lies in the nature of the missive. A pack of cards, sent from one party to another, would scarcely fail to excite suspicion; and it cannot be doubted that it is far better to secure ciphers from being considered as such, than to waste time in attempts at rendering them scrutiny-proof, when intercepted. Experience shows that the most cunningly constructed cryptograph, if suspected, can and will be unriddled.
An unusually secure mode of secret intercommunication might be thus devised. Let the parties each furnish themselves with a copy of the same edition of a book—the rarer the edition the better—as also the rarer the book. In the cryptograph, numbers are used altogether, and these numbers refer to the locality of letters in the volume. For example—a cipher is received commencing, 121-6-8. The party addressed refers to page 121, and looks at the sixth letter from the left of the page in the eighth line from the top. Whatever letter he there finds is the initial letter of the epistle—and so on. This method is very secure; yet it is possible to decipher any cryptograph written by its means—and it is greatly objectionable otherwise, on account of the time necessarily required for its solution, even with the key-volume.
It is not to be supposed that Cryptography, as a serious thing, as the means of imparting important information, has gone out of use at the present day. It is still commonly practised in diplomacy; and there are individuals, even now, holding office in the eye of various foreign governments, whose real business is that of deciphering. We have already said that a peculiar mental action is called into play in the solution of cryptographical problems, at least in those of the higher order. Good cryptographists are rare indeed; and thus their services, although seldom required, are necessarily well requited.
An instance of the modern employment of writing in cipher is mentioned in a work lately published by Messieurs Lea & Blanchard, of this city—“Sketches of Conspicuous Living Characters of France.” In a notice of Berryer, it is said that a letter being addressed by the Duchess de Berri to the legitimists of Paris, to inform them of her arrival, it was accompanied by a long note in cipher, the key of which she had forgotten to give. “The penetrating mind of Berryer,” says the biographer, “soon discovered it. It was this phrase substituted for the twenty-four letters of the alphabet—Le gouvernement provisoire.”
The assertion that Berryer “soon discovered the key-phrase,” merely proves that the writer of these memoirs is entirely innocent of cryptographical knowledge. Monsieur B. no doubt ascertained the key-phrase; but it was merely to satisfy his curiosity, after the riddle had been read. He made no use of the key in deciphering. The lock was picked.
In our notice of the book in question (published in the April number of this Magazine) we alluded to this subject thus—
“The phrase ‘Le gouvernement provisoire’ is French, and the note in cipher was addressed to Frenchmen. The difficulty of deciphering may well be supposed much greater, had the key been in a foreign tongue; yet any one who will take the trouble may address us a note, in the same manner as here proposed; and the key-phrase may be either in French, Italian, Spanish, German, Latin, or Greek, (or in any of the dialects of these languages,) and we pledge ourselves for the solution of the riddle.”
This challenge has elicited but a single response, which is embraced in the following letter. The only quarrel we have with the epistle, is that its writer has declined giving us his name in full. We beg that he will take an early opportunity of doing this, and thus relieve us of the chance of that suspicion which was attached to the cryptography of the weekly journal above-mentioned—the suspicion of inditing ciphers to ourselves. The postmark of the letter is Stonington, Conn.
S——, Ct., April 21, 1841.
To the Editor of Graham’s Magazine.