AGAIN we are asking cipher fans not to be backward in submitting ciphers and cipher solutions. The editor of Solving Cipher Secrets likes to hear from enthusiasts even though they have succeeded with only the simpler of the ciphers. Try some of these that we are publishing herewith.
How one cipher may become the foundation of another and more complex system is aptly illustrated by the United States Army "double transposition" cipher.
For this cipher is merely the "single transposition" system described with methods of solution in recent issues, applied twice successively, instead of only once, in the encipherment of a given message. To explain this system, the message SEND RE-ENFORCEMENTS will here be enciphered, using the key word ENSIGN.
As in the single transposition system, the processes of encipherment and decipherment are here governed by a numerical key, derived from a key word or key phrase by numbering its letters serially from 1 up in alphabetical order, taking repeated letters, if any, from left to right. For example, the key word ENSIGN (a) treated in this manner provides the numerical key (b) 1-4-6-3-2-5, in this instance.
Having determined the numerical key, the message may now be transcribed in successive lines, or horizontals, left to right, of the same length as the key, forming a number of columns, each of which is headed by a key number, as shown at (c).
(a) E N S I G N
(b) 1-4-6-3-2-5
(c) S E N D R E
E N F O R C
E M E N T S
A E . . . .
(d) S E E A R R
T D O N E N
M E E C S N
F E . . . .
(e) STMF-RES-ANC-EDEE-RNN-EOE
(f) STMFR ESANC EDEER NNEOE
At this juncture, the letters of the message must be counted. And if the total is not a multiple of five, 1, 2, 3, or 4 "null" or "dummy" letters must be added to increase it to such number. Frequently used letters, such as E, T, O, A, N, I, R, S, H, D, should be employed for this purpose in preference to the less frequently used ones, as J, K, Q, X, Z. In this instance A and E have been added, making twenty letters in all.
Having set up the message in this manner, the first transposition is effected by taking the columns, or verticals, of diagram (c) downward and in the order indicated by the numerical key, and transcribing the resultant series by successive rows, or horizontals, into the diagram (d). In this form the cipher is identical with the single transposition cipher previously mentioned.
To proceed with the encipherment, however, exactly the same process is repeated for the second transposition. Diagram (d) is taken by descending verticals in the order indicated by the numerical key, as before, forming the doubly transposed series (e). Grouping by fives (f) completes the encipherment, and in this form the cryptogram is ready for transmission.
To decipher a communication in this system with the key, the transpositions just described are merely reversed. First, however, the decipherer should prepare two similar diagrams of the required dimensions—four lines and six columns in this case—taking care to leave the proper number of blank spaces at the end of the last line of each diagram.
Next, the cryptogram (f) is transcribed into one of these diagrams by descending verticals as indicated by the numerical key, forming the arrangement (d). In turn (d) is taken by successive horizontals and transcribed into the other diagram by descending verticals in the same order, restoring the message to its original order (c), where it is ready for division into words.
This cipher is very easy to use, requiring only paper and pencil, the key, and a working knowledge of the system. As a military cipher it is authorized for use by all arms, but only in cases of emergency.
Like the single transposition system, several messages of the same length and key in this cipher are capable of solution by the multiple anagram method described last week. Four such cryptograms are offered the reader herewith under cipher No. 106 for solution in this manner.
In the next issue another double transposition cipher will be published in the same key as these, but of a different length. See if you can decipher the subjoined examples. Then try to find the numerical key.
Last week's straight substitution cipher was a corker! If you don't believe it, read the message: "Pusillanimous pilfering predatory pickaninnies purloined pious Presbyterian preacher's pecuniary perquisites."
The alphabet was formed by taking A (cipher) for the third letter C (message), and counting out every third unused letter thereafter in rotation, using B (cipher) for F (message), C for I, and so on. Did you get it?
No. 102 was enciphered by writing for any given letter the one next above it on the Underwood typewriter keyboard; using q for A, g for B, d for C, and so on. The message: "Many apparently secret ciphers are often not difficult to solve after a few minutes' study, and this one is no exception.
Ciphers like this may be solved without a typewriter keyboard in the same manner as Poe's famous Gold Bug cipher. With the keyboard at hand, however, the determination of even a single symbol, as for example, that 4=E, would lead to the discovery of the entire alphabet.
Transposition ciphers No. 103 were enciphered with the numerical key 4-1-5-3-6-2-7, derived from the key word GATEWAY. The messages: (a) Did you get this first? (b) Whether you solve this cryptogram first or the shorter one, you will hold the key to both.
Besides the transposition ciphers, this week's offering also includes an easy, straight substitution cipher. No. 104; and a simple multiple alphabet cipher. No. 105, the secret to which you should discover without a great deal of experimentation and with no need of tables or other paraphernalia.
CIPHER No. 104.
PWC DCQC LRRQCWCSGNES EX L UEDNSA CONT WLG RHP DLSJ NSPE L GNPHLPNES EX HPDEGP YLSACQ.
CIPHER No. 105 (L. E. L., Atlanta, Georgia).
OQWLNTN JU TQ ICUH CWW TGDVHN XKOP GKQH JV PWW.
CIPHER No. 106 (United States Army double transposition).
(a) FEREC TAORN OEANE DSNNE
CMSET
(b) AAEDD NOTCV NEYOA RWATN
IGOAN
(c) IPUPD SUTSL EURET SORXR
AEAEH
(d) CFYON AETSR ENEIG MEEER
AERRT