book cover
From FLYNN's May 22, 1926


Edited by M. E. Ohaver

WELL-SEASONED cipher, if centuries of service count for anything, and yet one that, though cumbersome to use, is still worthy of consideration by virtue of its relative security, is the book cipher.

Book cipher is of the substitution class, the substitutes usually being numbers that indicate certain letters or words in certain lines, paragraphs, columns, or pages of the article, pamphlet, book, or other publication used as a key.

The ways of using this cipher are too numerous to mention, this being merely up to the ingenuity of those contemplating the secret correspondence. A common method is to represent each word of the message by a group of three numbers. For instance: 127-4-11 would indicate the 11th word of the 4th line on the 127th page of the key volume.

The use of book cipher probably dates from Gutenberg's invention, in 1450, of printing with movable types. Previous to this time, and even up to the latter part of the fifteenth century, all books and all public and private documents in Europe were wTitten by hand. And manuscript, unless the key volume be sent along with the message, does not lend itself readily to this kind of cipher.

At any rate, some of the earliest writers on cryptography give details of the cipher. One of the first to mention it is Giovanni Battista della Porta, whose "De Furtivis Literarum Notis" was published at Naples in 1563.

And Blaise de Vigenère, the French writer, comments at some length on it in his "Traicté des Chiffres"—Paris, 1586. That he was well aware of its inconveniences is evidenced by the following quotation from his work.

"Now, " says Vigenère, " this plan is too laborious, and slow in operation for business requiring to be described in detail; it will not always provide the words sought for, at least, without an immense deal of pains, perhaps after examining through some hundred pages; and unless a dictionary be used, the names of persons, places, or professions, can be found in no book whatever.

" Besides which, " he continues, "many accidents may lead to a discovery of the key or book so confided in; and many others may happen to deprive us of that resource, or to render it inconvenient to depend on such a stratagem. The writing, moreover, is always liable to suspicion if intercepted,"

Book cipher has received its share of attention from writers of detective stories. Emile Gaboriau uses it effectively in his " Monsieur Lecoq"—first published in 1869, as also does Sir Arthur Conan Doyle in "The Valley of Fear," 1914.

Gaboriau quickly disposes of the cipher by having his detective, Lecoq, seize upon the only book—"The Songs of Beranger"— In the possession of his prisoner.

But in Doyle the situation is handled more skillfully, for Sherlock Holmes, with his customary logic, makes short work of arriving at the identity of the key volume. To outline briefly the story of the Doyle cipher, Holmes receives a cryptogram, which, from its appearance, he judges must be in book cipher.

The cipher is from an individual who wants him to read the message. Therefore, Holmes concludes that the key volume must be some book that his correspondent knew he possessed.

From a number in the cipher interpretable as a page indicator. Holmes is able to form some estimate of the size of this key volume. Further, by a similar inference, he decides that the book is one having two columns to the page.

Pursuing this line of reasoning, Holmes narrows down the search, and finally places his hand on the very volume—an edition of "Whitaker's Almanack "—that his correspondent had employed.

If properly used, book cipher should be proof against solution without the key volume. But to afford a maximum of difficulty against unauthorized decipherment, different substitutes should be employed for repeated words of a message, and the use of substitutes that represent consecutive words in the key should be avoided.

A frequently used variation of the book cipher, and one mentioned above by Vigenère, is that employing a dictionary as the key volume. The is commonly called dictionary cipher.

The should not be confused, however, with the dictionnaire chiffre used in France, and elsewhere, in the eighteenth century and after.

Dictionnaire chiffre consists of a specially prepared vocabulary of letters, letter groups, words, phrases, et cetera, arranged in dictionary order, that is, alphabetically, and numbered so that any term has its numerical equivalent in cipher.

The type of cipher was generally employed as an official and military cipher by the English Colonies, now the United States, during the American Revolution. It is an early form of code, and will be dealt with more fully in a later article.

Ordinary dictionary cipher may be used in various ways. A common method is to represent a given word in cipher by the word occupying the same location—counting defined words only—of the corresponding column of an agreed number of pages forward or backward in the dictionary.

Thus, suppose that a desired word is the 9th word in the 2nd column of page 63 in the particular dictionary being used, and that key for encipherment is: turn forwards three pages. The cipher substitutes for this word would then be the 9th word in the 2nd column of page 66.

Here is an example of a cipher of this kind, it being an actual message sent by a Democratic agent in the electoral campaign that followed the Presidential election of 1876, and enciphered with an edition of Webster's Pocket Dictionary.

Message: Dispatch  receive(d).  Will    do
       as        request(ed) if  it  will s  ecure
       several  elector(s).  Act          promptly.
Key: To decipher: turn back three pages.

An objection to the dictionary cipher, also true of the ordinary book cipher, is that wanted words are not always to be found in the key volume.

The difficulty is usually overcome by supplementing these ciphers with another cipher, usually of the simple substitution type, to encipher such words.

Again, the ordinary dictionary does not contain the various grammatical inflections of words, and consequently these terminations are frequently unexpressed in cipher, being determined by context.

To illustrate this point, in the above campaign cipher, RELIQUARY, RIGHTEOUS, and ENLIGHTEN actually represent receive, request, and elector, respectively, in the dictionary; while the intended forms are obviously as given in parentheses.

Sometimes a special cipher is used for these terminations. By another and rather transparent method, the ending of the substituted word is modified to conform with that of the intended word. By this device, RELIQUARIED, RIGHTEOUSED, and ENLIGHTENS, would have been used.

In another type of dictionary cipher, each word is represented by a series of numbers, indicating the page, column, and location of the word in the column.

For instance, 63-2-9 would by this method be interpreted as meaning the 9th word in the and column of page 63 of the key dictionary. The variety of the cipher was employed during the World War by Hindus in this country, who were plotting with the Germans for a revolution that would overthrow British rule in India.

As used by the brothers Lee—Arthur, Richard Henry, and William—the dictionary cipher was extensively employed during the.American Revolutionary period—the page being indicated by an Arabic numeral, the column by a letter a or b, and the line by a Roman numeral.

These forms of dictionary cipher are, of course, open to the same objections as the previously described variety. But the difficulty with grammatical inflections can be relieved somewhat by using a foreign language dictionary, such as English-German, or English-French, where many of the inflections follow words in their definitions. By this method the suffix, when given, can be expressed by an additional number indicating the particular ending desired.

There are still more serious faults with dictionary ciphers as a class, however, than the minor imperfections already mentioned. For ordinarily the particular dictionary used can be discovered when a collection of dictionaries is available for examination..And also, it is possible to solve the cipher without the dictionary by a process of alphabetical approximation, which will be covered later. There is a great affinity between book ciphers and the simple device of indicating significant letters, syllables and words, by marks in any piece of written or printed matter, as described in the last article.

The principal difference here is that in the one instance the key volume does not need to be sent with the cryptogram, the significant terms being referred to by the characters of the cipher; while in the other case the writing used as the key must accompany the cryptogram, with the significant letters, syllables, or words indicated by the marks.

Passing now from this general discussion of book ciphers to a particular example of them, what might have been one of the most amazing uses of cipher in all history will now be briefly related.

The cipher message referred to was claimed to have been intercepted during its transmission from a German to an.American station, which was said to have communicated it to a diplomatic agent of the former country at Washington. But as a matter of fact, the message was never sent from the German station, never was received in this country, and never was forwarded to the agent at Washington.

The alleged message that figured in this astonishing incident was linked by the fabricator of the story with the sinking of the Lusitania.

The cipher message was claimed to have originated at a great wireless station in Germany, and its intended destination was said to have been a certain station in this country, in use at the time by German plotters to transmit military information to their Foreign Office, in violation of the neutrality of this country.

As the story goes, it was discovered that the intercepted message, obviously in cipher, had been written in book cipher, the key volume being the New York World Almanac for 1915, and the numbers of the cipher referring to the pages, lines, and words of the almanac, after the general run of book ciphers.

The communication was deciphered, supposedly, amid the greatest excitement, the translation proving to be an order from the German government for its agent here to warn travelers against embarking on a voyage across the Atlantic on ships flying the British flag.

Prospective passengers were to be advised through notices inserted in the press that such ships were liable to destruction in waters adjacent to the British Isles.

That such notices were really published, and that the Lusitania was sunk, are, of course, matters of history. The point is that these things, admittedly inspired by Germany, were not advised by this supposed wireless message. Upon government investigation the whole affair was thoroughl y discredited, and retracted later as palpably untrue.

But while the cipher that figured in the case was thus not authentic, its constructor was careful enough to make it a real cipher. For the message had actually been enciphered with the almanac mentioned, and was capable of decipherment by its means.

Here, then, is a cipher of more than ordinary interest. For aside from the importance of its connections, it is a cipher that is at once spurious and genuine, and such ciphers, surely, are not to be encountered every day.

Were all of our readers provided with copies of the World Almanac for 1915, the original of this cipher might be printed here for solution.

But since this is impracticable, the substance of the message conveyed by this original has been enciphered in book cipher, as shown in cipher No. 1, by means of another key volume.

The is probably the first time in magazine history that a real book cipher has been offered for solution without divulging the name of the book used as a key.

So here is an opportunity for readers of FLYNN'S to use some logic à la Holmes in determining the identity of this book. To solve the problem, the key volume must first be discovered; and then the method of using it.

What is the key volume?

And how is it used?

These things you must learn for yourselves!

CIPHER No. 1 (Book cipher).

41-26; 43-10; 42-2; 42-7;
40-21; 42-12; 41-28; 43-19;
41-35; 41-32.


Ciphers more interesting than the following group of five, submitted by readers of FLYNN'S, would be very difficult to find, indeed!

Each cipher here presents a problem well worthy of your study. And, although we believe that you should succeed in solving them all, in no instance will one of these ciphers yield up its secret widiout a struggle that will mean time well spent.

For a flying start, begin by reading Mr. Morello's letter, subjoined, concerning his adventures in Brazil. Follow this up, of course, with a trial at his cipher.


I am submitting a cryptic message in a system due to my ignominious incarceration in a Brazilian village some years ago, while touring with a friend of mine.

This code resulted thus: My friend and I happened into a little town in Brazil called, I think, Ajonto. We landed there at night, so decided to satisfy our curiosity as to the tales we had often heard concerning the dilapidated conditions of some of the Brazilian villages.

Our curiosity caused our downfall. For, while strolling along some dirty street, we were slugged and robbed. When I "came to" my chum and I were in the dirtiest and filthiest hole on this planet.

Our jailers were the most degraded and inhumaij monsters God gave life to. Why they kept us prisoners, I cannot imagine, unless they thought they might secure a ransom for our release, being Americans. Eventually my chum and I decided that a code would come in mighty handy should we become separated. So we devised a code, and just in time. For no sooner had we understood each other than my chum was taken out and placed in a hovel opposite.

Although we could see each other, we could not communicate. So, after bribing one of the numerous waifs with a few pennies the robbers had overlooked, my chum and I were in constant communication with each other, using the code.

One of these messages was intercepted by one of the men, but it being meaningless to him, he let it go.

Needless to say, the code resulted in our escape. And eventually, by working here and there, we finally came hack to God's country. The inclosed message is in the code we used in our escape. It is simple when you know the method of solution. But without this. I guarantee it will cause some one a bad night.


Toronto, Ontario.

CIPHER No. 2 (Jos. J. Morello).

B C O 1 1 3 T U V W 2 H H P Q W N 2 9 I R S 6 2 3
S 9 2 C G H 8 1 W 9 P 6 2 4 8 H P Q 3 E 9 2 R R R      
9 8 I P Q 4 5 S W N 7 7 T 9 H 6 2 1 E Z Y X 2 R P
Q 9 8 E Q 4 4 S 9 1 6 U P M L 6 6 L 9 3 T M P 6 O
S 4 F F 6 M P 4 9 6 Y L N L 4 I L M 6 M 9 4 P 6 1
R 7 I W W Z 9 S 9 9 O P M N 6 N P R 3 M 9 9 E E E
W 6 N M P Q R S A B 6 T.

Mr. Krieger, Buffalo, New York, next submits a fine cipher, using a simple numerical alphabet, modified in cipher by the addition of key numbers. A consideration of the groups representing short words should be a big asset in solving this one.

CIPHER No. 3 (A. Krieger).

22-16-15-19-6-10   2-22   14-11-7-
18-14-13-15-28   2-22   7-17-18-24
16-8   17-17-21-24-10-24   20-22-21-
9-10-26.   24-3-23-7-13   16-23-23
7-17-21   21-1O-8   4-17-4-23-25

Recently a correspondent suggested that some ciphers be printed occasionally in systems that had previously been discussed in the department, so that the fans would not "get rusty" on the methods for these ciphers. The is a good idea. And in compliance with it the next two ciphers have been included in the present collection.

No. 4, submitted by Mr. Walker, Akron, Ohio, is a straight Gronsjeld cipher, which was described in full, with a method of solution, in FLYNN'S for June 6, 1925.

CIPHER No. 4 (M. Walker).


And to Mr. Meerdink, Hoboken, New Jersey, we are indebted for the following excellent example of the Nihilist transposition cipher, dealt with in the March 20 issue.

CIPHER No. 5 (J. G. Meerdink).


To round out this unbeatable combination, try your hand now at No. 6, an intriguing problem by G. A. Ferrell, D. D . S., Bessemer, Alabama, who writes about it as follows:

This cipher can he read at sight by one who knows the principle, but it is a hard nut to crack otherwise. Neither frequency nor recurrence is positive, although it sometimes happens that a word is represented twice by the same numbers. This method can be varied enough so that it will baffle any one who had solved this one.

CIPHER No. 6 (G. A. Ferrell, D. D. S,).

40 28 13 23 23—14 28—33 29—33 33
40 26 13—30 33 16 05—24 35—26 25
29 38 35 27 09 11 12—19 19 14 29
28 13 23-27 28—39 28 13 23 23—
06—20 27 23 33 38—23 24 41—40 35—
18 21 43 41 36 35 22 25 19 17 24 33—
45 35—28 14 20 39 25 23—38 28 17
28—33 29 17 14 17—24 22 12 14 19
17 08—25 21 12 16 24—35 17 21 29
14 19 17 08—25 28 23 36 28 15 28 —
21 15 18—20 21 23 37 24 27 27 23 19
15 17 08—11 18 37 39 28 33—32 14
08 08 27 35 23 19—14 28—23 19 24
23 21—08—24 38 29 18 09 23 24 27
33—35 38 33 29—22 16 10 21 25 23
21—27 28 17 38—25 18 13 14 18 —
07 23 39 32 23 23 21.

Submit your solutions to as many of the above ciphers as you are able to solve, together with any suggestions and comments. If you wish, you might send along a cipher of your own making also, to puzzle your fellow readers. Answers to the present ciphers will be printed in the next cipher article.


The holes in the tablet, in the first of the April 24 ciphers, represented the letters of the alphabet. Check up carefully and you will find that the order of the letters follows in the diagrammatic table printed herewith. We read from top to bottom and bottom to top in the successive columns. The whole alphabet is here with the exception of the I and J, which are treated alike.

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

By starting at the single knot, and substituting the above letters for the holes in the order that they are taken by the cord, the following message is deciphered:


Double letters can be enciphered in this system by using a special hole, or another letter, as X, for a repeater.

Cipher No. 2 was based on the following simple numerical alphabet:

A   B   C   D   E   F   G   H   IJ   K   L  M
4   22  10  9   1   11  13  18  3   19  12  8
N   O   P   Q   R   S   T   UV  W   X   Y   Z
20  2   21  23  7   6   5   15  14  17  16  24

To decipher this cryptogram, it should first be transformed into a numerical cipher, as at f a), by counting the letters between successive dots.

(a) 3-6-18-4-12-12-6-I-I —etc. 
(b) I S H  A L  L  S E E —etc.
(c) I shall     see      —etc.

The series of numbers, partly deciphered at (b), according to the above alphabet, can then be solved as a simple substitution cipher.

The answer to No. 3 (J. R. Midford), the first solver of which will receive a year's subscription to FLYNN'S, free, will be given in the next installment of the department.

In cipher No. 4 (Philo B. Horton), each rectangle represents a letter of the alphabet, thus:

W X r T M

In enciphering, the letters of the message are numbered from 1 up, these numbers then being placed in order in the rectangles representing the respective letters.

Without the key, by assigning arbitrary values to the rectangles, and rearranging these values serially according to the numbers, it is obvious that the cipher can be deciphered by simple substitution methods. The text of this cipher is : " Cryptography, which is one of the finest products of man's mental exertions, is most frequently put to some base purpose."

To read No. 5 (Leo Goldsmith), it is only required to take the first word of each sentence. The message: " Do you believe that it is always best to read FLYNN'S first? I do! "

The translation of No. 6 (A. P. Schmutz), is: "Solving Cipher Secrets is a wonderfully comprehensive department. May it flourish long! "

In the cryptogram, the characters following each italicized capital letter indicated the location of that letter in the message, in accordance with a key consisting of (1) twenty-six capital letters, (2) twenty-six small letters, and (3) numbers from 1 to any limit; as much of this key being used in any instance as the intended message requires.

In enciphering, the message and key are written out, so that each letter of the former is placed with a character of the latter. Some sections of the present message, and the corresponding parts of the key, are subjoined.

Key:   A B C D . . . U V W X Y
Text:  S O L V . . . I S A W O 

Z a b c d e f g h . . . V W X
N D E R F U L L Y . . . D E P

y z l 2 3 4 5 6 7 8 9 10 ——etc.
A R T M E n T M A Y I T  ——etc.

Each letter of the alphabet occurring in the message may now be located by the characters of the key with which it is written. Thus : A—W, y, 7; means that an A occurs with each of the three key characters by which it is followed, all of these being shown in the above short example.

In the original cryptogram, the first fourteen italicized capitals were arranged by Mr. Schmutz to spell "FRIDAY WE MUST GO," purely for purposes of confusing the would-be decipherer.

An interesting feature of No. 7 (A. W. Sweeten), is the foilowing triangular key, which provides three-figure substitutes for the letters of the message.

Triangle Key

The key was a fortunate discovery with Mr. Sweeten, who writes that he saw the triangular diagram in a newspaper with the question: " Can you make this without taking your pencil off the paper, or going over any line more than once?" Noting that it was composed of twenty-five smaller triangles which could represent the letters of the alphabet, he decided to use it as an alphabetic key, as it was different from that of the Nihilists, which used two characters to locate a letter, and Dr. Blair's, which used four.

(a)  P    A   R     T           -etc.
(b)  431  111 515   524         -etc.
(c)  4311   1151   5524         -etc.
(d)  634578 061075 742254       -etc.
(e)  63 45 78 06 10 75 74 22 54 -etc.

Mr. Sweeten's message is : "Parties of men and girls were already passing the hotel on their way to the little railway station." It isn't as hard as it looks.

In enciphering, the letters, a few of which are shown at (a), are replaced at (b) by the three-figure substitutes, which are regrouped by fours, at (c). At (d) a second substitution occurs, the four-figure groups being supplanted by their equivalents in six place Briggsian or common logarithms. These are regrouped by twos, at (e), completing the encipherment.


"The king is dead. Long live the king! " The might aptly be said of that kingly cipher, the Vigenère chiffre carré, featured in February 20 Solving Cipher Secrets. For if ever a cipher was riddled it was this one, as the appended list will show. And yet, being endowed with perennial youth, we have no doubt that it will continue to hold high its head in the world of ciphers, ever surrounded by a coterie of admirers who fancy they see strength in its apparent security.

The fans went right through the Confederate ciphers, too! And the interest displayed in these lead us to believe that they would like to have a chance also at the ciphers used in Civil War times by the Federals. Consequently, these may be forthcoming in an early issue. Watch your FLYNN'S carefully if you are interested.

Names accredited with equal numbers of solutions in the following list are arranged in the order submitted.

Look them over!

Mr. Winsor has also succeeded in solving the No. 7 (C. B. Petree) in the October 31, 1925 issue, the translation of which is : "I DEFY THE WORLD TO DECODE THIS CIPHER!"

Mr. Petree's cipher is a modification of Bacon's biliteral cipher—see FLYNN'S for April 25, 1925—using a binumeral alphabet in which A=11111, B=11112, C=11121 . . . Z=22121, the various groups of which are substituted, as at (b) for the letters of the message.

(a) I     D     E     F     Y    —etc. (b) 12112 11122 11211 11212 22112—etc.
(c) andit beany easil ierdo nteat—etc. (d) And it be any easilier don't eat—etc.

In the second substitution, shown at (c), any desired letter from a to m is used for a figure 1, and any letter from n to z for a figure 2. At this point, to puzzle the uninitiated, Mr. Petree chose letters forming a more or less intelligible sequence of words in the finished cryptogram. But the wise ones were not deceived.

Solvers of March 20 ciphers will be listed in the next issue of the department. In the meantime, fans, do your best with the ciphers in this issue. A little application and a lot of thought will work wonders.