A CCORDING to Sir Francis Bacon, one of the virtues of ciphers is that they be, in some cases, without suspicion
It is not at all difficult to imagine conditions when it would not be practicable for cipher communications to be recognized as such. This feature was therefore incorporated as the final requirement in the list of standards published in FLYNN'S WEEKLY for May 28. And a few of the many plans for diverting suspicion will be mentioned in this article.
Numerous ciphers have been devised especially with the object of avoiding suspicion. The word-grille, where the words of the real message are written through openings in a grille and the spaces between them filled in with other words to give the communication another meaning, is a very old example of such systems.
In other ciphers of this same general class the significant words or letters occupy certain places in the cryptogram as governed by prearranged keys. This obviates the irregular spacing of the word-grille, but it is difficult to avoid forced wording in any of these ciphers.
Bacon's celebrated biliteral cipher is probably the most famous system ever devised to divert suspicion. This cipher was fully explained in FLYNN'S WEEKLY for April 25, 1925, with an illustrative message in the form of a cartridge belt.
Many ciphers not intended to avoid suspicion readily lend themselves to that end by reencipherment, or the use of different vehicles of communication.
Distances in inches between knots tied in a string, for example, could be made to signify letters according to their alphabetical places; one inch representing A; two inches, B; and so on. A piece of yarn conveying a cryptogram in this way, to still further divert suspicion, could be knitted into some common object, as a sweater.
Sent by telegraph the symbols of such a cryptogram would be transformed into a series of electrical impulses. By the "sweater" route they become knots on a string, which the receiver translates back into cipher symbols and then deciphers in the regular way.
Such illustrations could be multiplied indefinitely. But these few examples may suffice to show how suspicion can be diverted, more or less, from almost any cipher. Whether or not such transformations are clever enough to baffle the investigator is, of course, an altogether different proposition. These eagle-eyed individuals make it a rule to view everything with suspicion, and to overlook nothing, however innocent it may appear.
The solution to No. 41, the continuously written key-phrase cipher published in the July 9 issue, used the Latin phrase, "Non semper temeritas est felix," as key. The message was a quotation from Porta, the Italian physicist, inventor of the camera obscura, and author of an important old work on cryptography.
Whenever any of us find it expedient to set down the hidden counsels of our mind, and want to prevent our letters, when intercepted by spies, patrols, or watches, from revealing our plans, we fly to cipher to afford us some guarantee.
In response to inquiry, the solutions to the two Austin key-phrase ciphers of March 5, "Edaolu oe oludluv," and "Ruyllye aol oludlu," were "Father of heralds," and "Guillim the herald," respectfully. The difficulty here was no doubt with the proper name "Guillim," who, Austin explains, was the earliest English herald of note.
Cryptogram No. 45 conveyed the message: "Our agent reports that man with crooked right thumb is responsible for recent holdups. Watch out for him." The alphabet was based on the keyword HOLDUP, as follows:
A B C D E F G H I J K L M H O L D U P Z Y X W V T S N O P Q R S T U V W X Y Z R Q N M K J I G F E C B A
No. 46 (Herbert Lancaster). was a Gronsfield cipher, using the date July 23, 1927 (=7231927) as key. This type of cipher was fully described, with methods of solution in FLYNN'S WEEKLY DETECTIVE FICTION for June 6, 1925. To encipher in this system write the digits of the key above the letters of the message, repeating the series as many times as necessary. Cipher substitutes are obtained by counting forward in the alphabet as indicated by the key figures. In this way the seventh letter from B is I; the second from A is C; and so on.
(a) 7 2 3 1 9 2 7 7 2 3 1 9 2 7 7 2 3 1 9 2 ... (b) B A N D I T S H A V E R E T R E A T E D ... (c) I C Q E R V Z O C Y F A G A Y G D U N F ...
The explanation of last week's No. 47 will not be published until readers have submitted their methods.
The first of this week's ciphers is a simple substitution affair. The other two illustrate methods of diverting suspicion. In No. 49 a box of candy has been selected as the communication vehicle. This box contains one hundred and twenty pieces of candy, all of the same shape, size, and color, but of five flavors, almond, lemon, orange, peppermint, and vanilla, as represented by the letters A, L, O, P, and V, respectfully, in the cryptogram.
To add zest to this problem, let us suppose that if the box is allowed to pass on to its destination unsuspected, certain papers of international importance will shortly be numbered among the missing. But if you can decipher this communication, possibly a trap can be set for the culprit. Cipher No. 49 shows how the candies are placed in the box. In deciphering, however, it may be necessary to "taste" them in another order.
Mr. Levine's No. 50 is an excellent example of the open letter cipher. This apparently guileless letter really conveys a secret message.
CIPHER No. 48.
QXGZ AZGFQPI XEPFDF QWF XEPFDXT WVT APKK SZGXNXG XEPFD BVPNXGFWKKC WJZVR JWVLPVT
CIPHER No. 49.
(Top Layer) Row 1 LVAPVVOPVPVA Row 2 LOALLPVVAVVOL Row 3 LPOLOLWAVAOIW (Middle Layer) Row t OAAALAALLOAPL Row 2 LLPLLPVOOLAOOL Row 3 OLLOLOOALPLLLL (Bottom Layer) Row 1 OOPVLLLOLLLLV Row 2 APWOPVOOLOLP Row 3 LLVALAVALOLLLL
CIPHER No. 50 (J. Levine, Los Angeles, California).
Come to-morrow at one thirty. Forgot
Saturday to remind you to bring refreshments.
Order something you wish, but remember, de-
liver it quickly. Yesterday, thirteen visitors
came inspecting our recently completed house.
We entertained ourselves card playing.
To offer a better chance to solve No. 50, its solution will not be published for three weeks. Complete explanations to Nos. 48 and 49, however, will be published next week. Next week's article will also describe the system used in cipher No. 44, published three weeks ago.
Without the key to this particular example, however, you will find matching the message and cryptogram a fascinating-task.