book cover
From FLYNN's May 14, 1927


Edited by M. E. Ohaver

AT first glance the somewhat Intricate cipher described below might seem relatively secure. But a closer inspection should reveal that it is not without its weak points.

To discover these vulnerable spots should provide a most interesting problem. Hence, no suggestions for solving the cipher will be offered here, thus affording readers the opportunity to work out their own methods.

The cipher in question is of the autokey class, using a simple numerical alphabet and an initial key number. The alphabetic arrangement may be regulated by any suitable method. That herewith is based on the key word JEWELS in the following manner:

First replace all repeated letters in the key word by dashes. Then write the remaining letters of the alphabet under this key, and in lines of the same length, thus:

J  E  W  —  L  S
A  B  C  D  F  G
H  I  K  M  N  O
P  Q  R  T  U  V
X  Y  Z

Finally, take the letters out of this arrangement by alternate verticals, and number them from 1 to 26, as follows:

1   2   3   4   5   6   7   8   9   10  11  12  13
J   A   H   P   X   Y   Q   I   B   E   W   C   K

14  15  16  17  18  19  20  21  22  23  24  25  26
R   Z   T   M   D   L   F   N   U   V   O   G   S

The communicating parties can select any number to act as the initial key. Here the number 10, which represents the alphabetic place of J, the first letter of the key word, has been employed.

To explain the system, the message, "WATCH THE MAN IN THE WHITE MASK, " will now be enciphered, using the above alphabet and initial key.

The first step consists in substituting for each letter of the message (a) its proper numerical equivalent in the cipher alphabet. Next, shift the resulting series of numbers (b) one place forward, as shown in line (c), so that each number in line (b) is used as a key number below the number next following it. The initial key number, 10, is used for the first letter. (See next page for illustration.)

The numbers in lines (b) and (c) are then added together, forming the series (d), in which form the cryptogram is ready for transmission.

In deciphering, the process just described is merely reversed. The initial key number, 10, is subtracted from the first cipher number, 21, giving the difference, 11, which signifies the first message letter, W, and becomes the key for 13, the next number of the cryptogram. Similarly, the difference between 13 and 11 is 2, which equals A, and is used as key for the next number; and so on.

(d) 21-13-18-28-15 ...
(c) 20 11 2  16 12 ...
(b) 11 2  16 12 3 ...
(a) W  A  T  C  H ... 

A given letter can be represented in this cipher by as many as twenty-six different numbers, depending upon the key numbers with which it is enciphered. In other words, the cipher uses twenty-six different cipher alphabets, the order of which is determined by the identity and order of letters in the message to be enciphered.

(a) W  A  T  C  H  T  H  E  M  A  N  I  N  T  H  E  W  H  I  T  E  M  A  S  K
(b) 11 2  16 12 3  16 3  10 17 2  21 8  21 16 3  10 11 3  8  16 10 17 2  26 13
(c) 10 11 2  16 12 3  16 3 10  17 2  21 8  21 16 3  10 11 3  8  16 10 17 2  26 
(d) 21-13-18-28-15-19-19-13-27-19-23-29-29-37-19-13-21-14-II-24-26-27-19-28-39

This might all seem very baffling. But as a matter of fact, the cipher is easy to solve. And the above example is long enough for experimental purposes in working out a method of solution.

When you have evolved your method, turn it loose on cipher No. 19. Mr. Olden, by the way, has hidden his initial key number at a prearranged place in his cryptogram. But this feature should occasion the decipherer no great trouble.

If you are successful with No. 19, send in your translation and method of solution.

Do your best now. Here goes!

CIPHER No. 19 (James Olden, Medicine Hat, Alberta, Canada).


No. 20 is a typewriter cipher. But before attempting its solution, read the following letter which relates an interesting experience with a cipher of this kind, and brings out the curious fact that, as far as this cipher is concerned, a typewriter is in reality a cipher machine.


The translation of cipher No. 4, in FLYNN'S WEEKLY for March 12, is: (Mr. Rossell here appends the correct solution.)

The enciphering and deciphering of this cipher is entirely mechanical. Use a doubleshift typewriter; lock down the figure shift key and type your message; the machine writes your cryptogram. Now lock down the capital shift key and copy the cryptogram; the machine will give you the translation.

Years ago I submitted a cryptogram made on this principle through one of the local newspapers to a number of persons who had boasted that they could decipher any cryptogram that had ever been devised. I told them there was no need of memorizing keys; and no code books were required; that all that was necessary was for the sender to write the message, and for the receiver to copy the cryptogram; and I challenged them to tell me how they did it. And not one of them could tell us how it was done, although one or two deciphered the cryptogram by the process described by Edgar Allan Poe in the Gold Bug.


Washington, D. C.

No. 20 is of the above mentioned type, although it was done on a different machine than was used for No. 4. If you have a typewriter and it happens to be the right make and model, you will only need to lock the figure shift and write the translation. Otherwise you must solve it by the usual methods. Can you do it?

CIPHER No. 20 (Geo. Abbott, Maiden, Massachusetts).

:3'34  $57;''#3  528?3  9'34  5*3
$@;3  $59:3  8$  -99%  @%'8?3
!94  5*3  $9#'34  9!  ?8o*34$

The solutions to last week's crypts are next in order:

No. 16—The hurricane swept in from the sea, accompanied by a falling barometer, heavy thunder, and a wind velocity of more than fifty miles an hour.

No. 17—Tritheim, Palatino, Collange, Porta, Bellasco, Dee, and Vigenere, are all authors of important sixteenth century works devoted to the subject of cryptography.

No. 18—Payroll bandits jailed yesterday plan break to-night, but extra guard should easily frustrate attempt.