The Complete Works of Edgar Allan Poe - Edgar Allan Poe [646]
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 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 Berrver," 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 keyphrase," 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