WITH the series of articles on the United States Army "double transposition cipher" just completed, we take this opportunity to present an ingenious variation of this system submitted some time ago by Charles Winsor, Boston, Massachusetts. It is a splendid cipher that you should find fascinating.
We have already demonstrated, in the army cipher, that a number of cryptograms of the same length and key could be combined for solution, and that the key could then easily be determined for use in translating similarly keyed cryptograms of all lengths.
In Mr. Winsor's variation, to compare the two systems, it is also possible to solve a group of cryptograms of the same length and key. But, as our correspondent puts it, even with the cipher and translation given there is still "a fiendish job ahead to discover the key."
The proposed variation is no more difficult to use than the original, and is only slightly more complex, the chief difference being in the use of two different keys instead of the same identical key twice in succession.
Thus, to encipher the message, HOSTILE ATTACK HAS BROKEN DOWN, with SIGNAL and SERVICE as first and second key words, respectively, first prepare the numerical keys (a) and (d) by numbering the letters in alphabetical order, taking repeated letters, if any, from left to right.
S I G N A L
(a) 6 - 3 - 2 - 5 - l - 4
(b) H O S T I L
E A T T A C
K H A S B R
O K E N D O
W N . . . .
(c) IABD—STAE—OAHKN—LCRO—
TTSN—HEKOW
S E R V IC E
(d) 6 - 2 - 5 - 7 - 4 - 1 - 3
(e) I A B D S T A
E O A H K N L
C R O T T S N
H E K O W . .
(f) TNS—ACRE—ALN—SKTW—BAOK—
IECH—DHTO
(g) TNSAO REALN SKTWB AOKIE
CHDHT O
Then transcribe the message under the first key (a) by successive horizontals so that each of the resultant columns will be headed by a key number, as shown at (h). Next, take the letters out of this formation by descending verticals in the order indicated by the first key, and transfer the resultant series (c) by successive horizontals, as before, under the second key (d), as illustrated at (e).
Finally, take this second formation by descending verticals in the order indicated by the second key, and group the resultant series (f) by fives for transmission (g). Decipherment is, of course, merely a reversal of the process just described.
It is interesting to note how Mr. Winsor's cipher tremendously increases the number of mathematically possible key variations over the regulation double transposition cipher. Thus, in the latter there are seven hundred and twenty po.ssible variations in a six-number key, and five thousand and forty in a seven-number key. As combined in the above example, however, these two keys alone are capable of three million six hundred and twenty-eight thousand eight hundred variations. And with longer keys we soar to still dizzier heights.
In Cipher No. 127, herewith, you will find a cryptogram in the above system, its translation, and a numerical series showing the exact order of transposition. Thus the first cipher letter is the sixteenth letter of the message; the second cipher letter is the twenty-seventh message letter; and so on. In other words, you have everything but the two keys. Can you discover them?
This promises to be interesting. So the key words will be withheld for a few weeks, and full results will be published later. If this doesn't add a few wrinkles to your brow nothing will. Anyway, let us know what luck you have.
Last week's No. 122 (L. A. Harper ) used a message alphabet based on the key word HARPER, with the standard typewriter keyboard as cipher alphabet, thus:
HARPEBC DFGIJKLMN OQSTUVWXYZ ZXCVBNM ASDFGHJKL QWERTYUIOP
The message: "Three cheers for Flynn's cipher department. Hope it will continue to be of much interest as at present. (Signed) Larry." Thanks, Larry ! We are all with you, and doing our best.
No. 123 (J. Lloyd Hood) used the key phrase, "Six slick slim saplings swayed," and expressed the message, "SIX SAPLINGS, SLICK.AND SLIM, SWAYED SOFTLY, SILENTLY." Full details of this type of cipher, with methods of solution and answers, were given in the January 23, 1926, and March 6, 1926, issues.
In this connection Paul Napier, Louisville, Kentucky, writes us that he has found an edition in book form of the novel Cipher, by Jane Goodwin Austin, mentioned in the second of the above issues, published by Sheldon & Co., New York, 1869. We are glad to pass this information on to the fans.
M. Walker's transposition cipher. No. 124, used a "checkerboard" of twelve columns and eight rows. The message: "We are the voices of the wandering wind, which moan for rest and rest can never find; Lo ! as the wind is so is mortal life."
The message was first spelled into the "light" squares by alternate verticals beginning at the upper left corner, italicized in the accompanying figure, and then into the "dark" squares by alternate horizontals beginning at the upper right corner. Not so difficult when you know how. But did you get it?
W S V E T R R D W N N A T E C F A E N D N A E T E N O I H F I R H E F V D H L O O D A N S O T S A D I N E I N W I E O H I T S S S N O I I M S E R L C A W T G R C O R M L E I E F A E W J H Q R
All of which being said and done, let's turn to this week's ciphers. Besides Mr. Winsor's difficult transposition problem, you will also find an interesting, but not so difficult, straight substitution cipher. No. 125, and a fine numerical cipher by Bernard G. Kobus, based on four simple arithmetical rules. Answers to Nos. 125 and 126 will appear next week.
CIPHER No. 125.
BU BJ GFFT UF VKO MXT WFYBJE FKV OVMBX MGMBXJU UEMU FI FUEAVJ.
CIPHER No. 126 (Bernard G. Kobus, Chicago, Illinois).
54-29-21-31-36-30 27-22-27-28-34-36 63-30 18-25-42 42-22-15-31 48-22-16-22-25-11-31- 13-42 54-26-25-11-31-6-51 63-51 18-25-42 27-6-14-29-41.
CIPHER No. 127 (Charles Winsor, Boston, Massachusetts).
NNIVR UEOAR FMIOD WYOEI TOADY ROSC MOVE YOUR DIVISION FORWARD AT ONCE 16-27-12-11-22 7-4-15-24-8 17-1-10-26-9 20- 5-18-29-14 25-6-21-23-3 19-2-13-28